Migrating from Oracle Database 19c to 26ai Free: Data Pump Practical Steps and Error Explanation

An increasing number of engineers are considering migrating from Oracle Database 19c to Oracle Database 26ai Free, the latest developer release. This article explains the steps to migrate data from a 19c environment to a 26ai Free environment using the standard Oracle Data Pump feature, based on hands-on verification.

We will focus specifically on uncovering the true nature of “errors occurring during full import” and the criteria for judging whether they can be safely ignored.

What You Will Learn in This Article

Data Pump migration steps from Oracle 19c to Oracle 26ai Free
Differences in import results between schema mode and full mode
How to identify “ignorable ORA errors” occurring during cross-version migration

Conclusion / Shortest Path List

Migration from 19c to 26ai Free can be performed smoothly using Data Pump (expdp/impdp), but errors will be output during a full import due to differences in system definitions.

Note: 19c is running in a Single (non-CDB) environment. 26ai is a CDB/PDB environment.

[19c] Confirm migration target data (HR schema, etc.) and create a directory object
[19c] Acquire dump file with expdp (Schema mode recommended; Full is also possible)
[26ai] Transfer the dump file to the directory on the 26ai server
[26ai] Execute impdp (Schema mode basically has no errors)
[26ai] For full import, check logs, scrutinize system-related errors, and ignore them

Prerequisite Environment and Basic Knowledge

Verification Environment

Source: Oracle Database 19c Enterprise Edition (Linux)
Target: Oracle Database 26ai Free (Linux / PDB: freepdb1)
Connection User: system (Administrator privileges)

What is Oracle Data Pump?

It is a utility for high-speed movement of data and metadata. It maintains high compatibility even for migration between different versions (e.g., 19c → 26ai). However, when performing a full export/import, warnings or errors may occur during import due to differences in version-specific system schemas or roles.

Practical Steps: Migrating from 19c to 26ai Free

1. Preparation and Export on Source (19c)

First, prepare sample data (HR schema) in the source 19c environment and create a directory for Data Pump.

HR Schema Installation (If not installed)

-- Execute in 19c SQL*Plus
CONN / AS SYSDBA
@?/demo/schema/human_resources/hr_main.sql
-- Enter password (hr), tablespace (users), temp tablespace (temp), etc. according to the prompts

SQL> @?/demo/schema/human_resources/hr_main.sql

specify password for HR as parameter 1:
Enter value for 1: hr

specify default tablespeace for HR as parameter 2:
Enter value for 2: users

specify temporary tablespace for HR as parameter 3:
Enter value for 3: temp

specify log path as parameter 4:
Enter value for 4: $ORACLE_HOME/demo/schema/log/


PL/SQL procedure successfully completed.


User created.


User altered.

:::

Comment created.


Commit complete.


PL/SQL procedure successfully completed.

SQL> conn hr/hr
Connected.
SQL> select table_name from user_tables;

TABLE_NAME
--------------------------------------------------------------------------------
REGIONS
LOCATIONS
DEPARTMENTS
JOBS
EMPLOYEES
JOB_HISTORY
COUNTRIES

7 rows selected.

SQL>

Creating Directory Object

CREATE OR REPLACE DIRECTORY dp_dir AS '/u01/app/dp_dir';
GRANT READ, WRITE ON DIRECTORY dp_dir TO system;

Export Execution (Schema Mode / Full Mode)

Execute expdp from the OS terminal.

# 1. Schema Mode (HR user only)
expdp system/oracle schemas=hr directory=dp_dir dumpfile=hr_exp.dmp logfile=hr_exp.log

# 2. Full Mode (Entire Database)
expdp system/oracle full=y directory=dp_dir dumpfile=full_exp.dmp logfile=full_exp.log

🖥️ Execution results using a real device

View execution results (click here)


[oracle@orcl19c ~]$ expdp system/oracle schemas=hr directory=dp_dir dumpfile=hr_exp.dmp logfile=hr_exp.log

Export: Release 19.0.0.0.0 - Production on Tue Jan 6 05:52:41 2026
Version 19.3.0.0.0

Copyright (c) 1982, 2019, Oracle and/or its affiliates.  All rights reserved.

Connected to: Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - Production
Starting "SYSTEM"."SYS_EXPORT_SCHEMA_01":  system/******** schemas=hr directory=dp_dir dumpfile=hr_exp.dmp logfile=hr_exp.log
Processing object type SCHEMA_EXPORT/TABLE/TABLE_DATA
Processing object type SCHEMA_EXPORT/TABLE/INDEX/STATISTICS/INDEX_STATISTICS
Processing object type SCHEMA_EXPORT/TABLE/STATISTICS/TABLE_STATISTICS
Processing object type SCHEMA_EXPORT/STATISTICS/MARKER
Processing object type SCHEMA_EXPORT/USER
Processing object type SCHEMA_EXPORT/SYSTEM_GRANT
Processing object type SCHEMA_EXPORT/ROLE_GRANT
Processing object type SCHEMA_EXPORT/DEFAULT_ROLE
Processing object type SCHEMA_EXPORT/TABLESPACE_QUOTA
Processing object type SCHEMA_EXPORT/PRE_SCHEMA/PROCACT_SCHEMA
Processing object type SCHEMA_EXPORT/SEQUENCE/SEQUENCE
Processing object type SCHEMA_EXPORT/TABLE/TABLE
Processing object type SCHEMA_EXPORT/TABLE/COMMENT
Processing object type SCHEMA_EXPORT/PROCEDURE/PROCEDURE
Processing object type SCHEMA_EXPORT/PROCEDURE/ALTER_PROCEDURE
Processing object type SCHEMA_EXPORT/VIEW/VIEW
Processing object type SCHEMA_EXPORT/TABLE/INDEX/INDEX
Processing object type SCHEMA_EXPORT/TABLE/CONSTRAINT/CONSTRAINT
Processing object type SCHEMA_EXPORT/TABLE/CONSTRAINT/REF_CONSTRAINT
Processing object type SCHEMA_EXPORT/TABLE/TRIGGER
. . exported "HR"."EMPLOYEES"                            17.08 KB     107 rows
. . exported "HR"."LOCATIONS"                            8.437 KB      23 rows
. . exported "HR"."JOB_HISTORY"                          7.195 KB      10 rows
. . exported "HR"."JOBS"                                 7.109 KB      19 rows
. . exported "HR"."DEPARTMENTS"                          7.125 KB      27 rows
. . exported "HR"."COUNTRIES"                            6.367 KB      25 rows
. . exported "HR"."REGIONS"                              5.546 KB       4 rows
Master table "SYSTEM"."SYS_EXPORT_SCHEMA_01" successfully loaded/unloaded
******************************************************************************
Dump file set for SYSTEM.SYS_EXPORT_SCHEMA_01 is:
  /u01/app/dp_dir/hr_exp.dmp
Job "SYSTEM"."SYS_EXPORT_SCHEMA_01" successfully completed at Tue Jan 6 05:54:28 2026 elapsed 0 00:01:42

[oracle@orcl19c ~]$ expdp system/oracle full=y directory=dp_dir dumpfile=full_exp.dmp logfile=full_exp.log

Export: Release 19.0.0.0.0 - Production on Tue Jan 6 05:55:30 2026
Version 19.3.0.0.0

Copyright (c) 1982, 2019, Oracle and/or its affiliates.  All rights reserved.

Connected to: Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - Production
Starting "SYSTEM"."SYS_EXPORT_FULL_01":  system/******** full=y directory=dp_dir dumpfile=full_exp.dmp logfile=full_exp.log
Processing object type DATABASE_EXPORT/EARLY_OPTIONS/VIEWS_AS_TABLES/TABLE_DATA
Processing object type DATABASE_EXPORT/NORMAL_OPTIONS/TABLE_DATA
Processing object type DATABASE_EXPORT/NORMAL_OPTIONS/VIEWS_AS_TABLES/TABLE_DATA
Processing object type DATABASE_EXPORT/SCHEMA/TABLE/TABLE_DATA
Processing object type DATABASE_EXPORT/SCHEMA/TABLE/INDEX/STATISTICS/INDEX_STATISTICS
Processing object type DATABASE_EXPORT/SCHEMA/TABLE/STATISTICS/TABLE_STATISTICS
Processing object type DATABASE_EXPORT/STATISTICS/MARKER
Processing object type DATABASE_EXPORT/PRE_SYSTEM_IMPCALLOUT/MARKER
Processing object type DATABASE_EXPORT/PRE_INSTANCE_IMPCALLOUT/MARKER
Processing object type DATABASE_EXPORT/TABLESPACE
Processing object type DATABASE_EXPORT/PROFILE
Processing object type DATABASE_EXPORT/SCHEMA/USER
Processing object type DATABASE_EXPORT/RADM_FPTM
Processing object type DATABASE_EXPORT/GRANT/SYSTEM_GRANT/PROC_SYSTEM_GRANT
Processing object type DATABASE_EXPORT/SCHEMA/GRANT/SYSTEM_GRANT
Processing object type DATABASE_EXPORT/SCHEMA/ROLE_GRANT
Processing object type DATABASE_EXPORT/SCHEMA/DEFAULT_ROLE
Processing object type DATABASE_EXPORT/SCHEMA/ON_USER_GRANT
Processing object type DATABASE_EXPORT/SCHEMA/TABLESPACE_QUOTA
Processing object type DATABASE_EXPORT/RESOURCE_COST
Processing object type DATABASE_EXPORT/TRUSTED_DB_LINK
Processing object type DATABASE_EXPORT/SCHEMA/SEQUENCE/SEQUENCE
Processing object type DATABASE_EXPORT/DIRECTORY/DIRECTORY
Processing object type DATABASE_EXPORT/SYSTEM_PROCOBJACT/PRE_SYSTEM_ACTIONS/PROCACT_SYSTEM
Processing object type DATABASE_EXPORT/SYSTEM_PROCOBJACT/PROCOBJ
Processing object type DATABASE_EXPORT/SYSTEM_PROCOBJACT/POST_SYSTEM_ACTIONS/PROCACT_SYSTEM
Processing object type DATABASE_EXPORT/SCHEMA/PROCACT_SCHEMA
Processing object type DATABASE_EXPORT/EARLY_OPTIONS/VIEWS_AS_TABLES/TABLE
Processing object type DATABASE_EXPORT/EARLY_POST_INSTANCE_IMPCALLOUT/MARKER
Processing object type DATABASE_EXPORT/NORMAL_OPTIONS/TABLE
Processing object type DATABASE_EXPORT/NORMAL_OPTIONS/VIEWS_AS_TABLES/TABLE
Processing object type DATABASE_EXPORT/NORMAL_POST_INSTANCE_IMPCALLOUT/MARKER
Processing object type DATABASE_EXPORT/SCHEMA/TABLE/TABLE
Processing object type DATABASE_EXPORT/SCHEMA/TABLE/COMMENT
Processing object type DATABASE_EXPORT/SCHEMA/PROCEDURE/PROCEDURE
Processing object type DATABASE_EXPORT/SCHEMA/PROCEDURE/ALTER_PROCEDURE
Processing object type DATABASE_EXPORT/SCHEMA/VIEW/VIEW
Processing object type DATABASE_EXPORT/SCHEMA/TABLE/INDEX/INDEX
Processing object type DATABASE_EXPORT/SCHEMA/TABLE/CONSTRAINT/CONSTRAINT
Processing object type DATABASE_EXPORT/SCHEMA/TABLE/CONSTRAINT/REF_CONSTRAINT
Processing object type DATABASE_EXPORT/SCHEMA/TABLE/TRIGGER
Processing object type DATABASE_EXPORT/FINAL_POST_INSTANCE_IMPCALLOUT/MARKER
Processing object type DATABASE_EXPORT/AUDIT_UNIFIED/AUDIT_POLICY_ENABLE
Processing object type DATABASE_EXPORT/POST_SYSTEM_IMPCALLOUT/MARKER
. . exported "SYS"."KU$_USER_MAPPING_VIEW"               6.070 KB      37 rows
. . exported "SYSTEM"."REDO_DB"                          25.59 KB       1 rows
. . exported "WMSYS"."WM$WORKSPACES_TABLE$"              12.10 KB       1 rows
. . exported "WMSYS"."WM$HINT_TABLE$"                    9.984 KB      97 rows
. . exported "LBACSYS"."OLS$INSTALLATIONS"               6.960 KB       2 rows
. . exported "WMSYS"."WM$WORKSPACE_PRIV_TABLE$"          7.078 KB      11 rows
. . exported "SYS"."DAM_CONFIG_PARAM$"                   6.531 KB      14 rows
. . exported "SYS"."TSDP_SUBPOL$"                        6.328 KB       1 rows
. . exported "WMSYS"."WM$NEXTVER_TABLE$"                 6.375 KB       1 rows
. . exported "LBACSYS"."OLS$PROPS"                       6.234 KB       5 rows
. . exported "WMSYS"."WM$ENV_VARS$"                      6.015 KB       3 rows
. . exported "SYS"."TSDP_PARAMETER$"                     5.953 KB       1 rows
. . exported "SYS"."TSDP_POLICY$"                        5.921 KB       1 rows
. . exported "WMSYS"."WM$VERSION_HIERARCHY_TABLE$"       5.984 KB       1 rows
. . exported "WMSYS"."WM$EVENTS_INFO$"                   5.812 KB      12 rows
. . exported "LBACSYS"."OLS$AUDIT_ACTIONS"               5.757 KB       8 rows
. . exported "LBACSYS"."OLS$DIP_EVENTS"                  5.539 KB       2 rows
. . exported "AUDSYS"."AUD$UNIFIED":"AUD_UNIFIED_P0"         0 KB       0 rows
. . exported "AUDSYS"."AUD$UNIFIED":"SYS_P181"           122.7 KB     148 rows
. . exported "AUDSYS"."AUD$UNIFIED":"SYS_P241"           59.52 KB      14 rows
. . exported "LBACSYS"."OLS$AUDIT"                           0 KB       0 rows
. . exported "LBACSYS"."OLS$COMPARTMENTS"                    0 KB       0 rows
. . exported "LBACSYS"."OLS$DIP_DEBUG"                       0 KB       0 rows
. . exported "LBACSYS"."OLS$GROUPS"                          0 KB       0 rows
. . exported "LBACSYS"."OLS$LAB"                             0 KB       0 rows
. . exported "LBACSYS"."OLS$LEVELS"                          0 KB       0 rows
. . exported "LBACSYS"."OLS$POL"                             0 KB       0 rows
. . exported "LBACSYS"."OLS$POLICY_ADMIN"                    0 KB       0 rows
. . exported "LBACSYS"."OLS$POLS"                            0 KB       0 rows
. . exported "LBACSYS"."OLS$POLT"                            0 KB       0 rows
. . exported "LBACSYS"."OLS$PROFILE"                         0 KB       0 rows
. . exported "LBACSYS"."OLS$PROFILES"                        0 KB       0 rows
. . exported "LBACSYS"."OLS$PROG"                            0 KB       0 rows
. . exported "LBACSYS"."OLS$SESSINFO"                        0 KB       0 rows
. . exported "LBACSYS"."OLS$USER"                            0 KB       0 rows
. . exported "LBACSYS"."OLS$USER_COMPARTMENTS"               0 KB       0 rows
. . exported "LBACSYS"."OLS$USER_GROUPS"                     0 KB       0 rows
. . exported "LBACSYS"."OLS$USER_LEVELS"                     0 KB       0 rows
. . exported "SYS"."AUD$"                                    0 KB       0 rows
. . exported "SYS"."DAM_CLEANUP_EVENTS$"                     0 KB       0 rows
. . exported "SYS"."DAM_CLEANUP_JOBS$"                       0 KB       0 rows
. . exported "SYS"."TSDP_ASSOCIATION$"                       0 KB       0 rows
. . exported "SYS"."TSDP_CONDITION$"                         0 KB       0 rows
. . exported "SYS"."TSDP_FEATURE_POLICY$"                    0 KB       0 rows
. . exported "SYS"."TSDP_PROTECTION$"                        0 KB       0 rows
. . exported "SYS"."TSDP_SENSITIVE_DATA$"                    0 KB       0 rows
. . exported "SYS"."TSDP_SENSITIVE_TYPE$"                    0 KB       0 rows
. . exported "SYS"."TSDP_SOURCE$"                            0 KB       0 rows
. . exported "SYSTEM"."REDO_LOG"                             0 KB       0 rows
. . exported "WMSYS"."WM$BATCH_COMPRESSIBLE_TABLES$"         0 KB       0 rows
. . exported "WMSYS"."WM$CONSTRAINTS_TABLE$"                 0 KB       0 rows
. . exported "WMSYS"."WM$CONS_COLUMNS$"                      0 KB       0 rows
. . exported "WMSYS"."WM$LOCKROWS_INFO$"                     0 KB       0 rows
. . exported "WMSYS"."WM$MODIFIED_TABLES$"                   0 KB       0 rows
. . exported "WMSYS"."WM$MP_GRAPH_WORKSPACES_TABLE$"         0 KB       0 rows
. . exported "WMSYS"."WM$MP_PARENT_WORKSPACES_TABLE$"        0 KB       0 rows
. . exported "WMSYS"."WM$NESTED_COLUMNS_TABLE$"              0 KB       0 rows
. . exported "WMSYS"."WM$RESOLVE_WORKSPACES_TABLE$"          0 KB       0 rows
. . exported "WMSYS"."WM$RIC_LOCKING_TABLE$"                 0 KB       0 rows
. . exported "WMSYS"."WM$RIC_TABLE$"                         0 KB       0 rows
. . exported "WMSYS"."WM$RIC_TRIGGERS_TABLE$"                0 KB       0 rows
. . exported "WMSYS"."WM$UDTRIG_DISPATCH_PROCS$"             0 KB       0 rows
. . exported "WMSYS"."WM$UDTRIG_INFO$"                       0 KB       0 rows
. . exported "WMSYS"."WM$VERSION_TABLE$"                     0 KB       0 rows
. . exported "WMSYS"."WM$VT_ERRORS_TABLE$"                   0 KB       0 rows
. . exported "WMSYS"."WM$WORKSPACE_SAVEPOINTS_TABLE$"        0 KB       0 rows
. . exported "MDSYS"."RDF_PARAM$"                        6.515 KB       3 rows
. . exported "SYS"."AUDTAB$TBS$FOR_EXPORT"               5.953 KB       2 rows
. . exported "SYS"."DBA_SENSITIVE_DATA"                      0 KB       0 rows
. . exported "SYS"."DBA_TSDP_POLICY_PROTECTION"              0 KB       0 rows
. . exported "SYS"."FGA_LOG$FOR_EXPORT"                      0 KB       0 rows
. . exported "SYS"."NACL$_ACE_EXP"                           0 KB       0 rows
. . exported "SYS"."NACL$_HOST_EXP"                      6.976 KB       2 rows
. . exported "SYS"."NACL$_WALLET_EXP"                        0 KB       0 rows
. . exported "SYS"."SQL$TEXT_DATAPUMP"                       0 KB       0 rows
. . exported "SYS"."SQL$_DATAPUMP"                           0 KB       0 rows
. . exported "SYS"."SQLOBJ$AUXDATA_DATAPUMP"                 0 KB       0 rows
. . exported "SYS"."SQLOBJ$DATA_DATAPUMP"                    0 KB       0 rows
. . exported "SYS"."SQLOBJ$PLAN_DATAPUMP"                    0 KB       0 rows
. . exported "SYS"."SQLOBJ$_DATAPUMP"                        0 KB       0 rows
. . exported "SYSTEM"."SCHEDULER_JOB_ARGS"                   0 KB       0 rows
. . exported "SYSTEM"."SCHEDULER_PROGRAM_ARGS"               0 KB       0 rows
. . exported "WMSYS"."WM$EXP_MAP"                        7.718 KB       3 rows
. . exported "WMSYS"."WM$METADATA_MAP"                       0 KB       0 rows
. . exported "HR"."EMPLOYEES"                            17.08 KB     107 rows
. . exported "HR"."LOCATIONS"                            8.437 KB      23 rows
. . exported "HR"."JOB_HISTORY"                          7.195 KB      10 rows
. . exported "HR"."JOBS"                                 7.109 KB      19 rows
. . exported "HR"."DEPARTMENTS"                          7.125 KB      27 rows
. . exported "HR"."COUNTRIES"                            6.367 KB      25 rows
. . exported "HR"."REGIONS"                              5.546 KB       4 rows
Master table "SYSTEM"."SYS_EXPORT_FULL_01" successfully loaded/unloaded
******************************************************************************
Dump file set for SYSTEM.SYS_EXPORT_FULL_01 is:
  /u01/app/dp_dir/full_exp.dmp
Job "SYSTEM"."SYS_EXPORT_FULL_01" successfully completed at Tue Jan 6 06:02:00 2026 elapsed 0 00:06:27

[oracle@orcl19c ~]$ ls -l /u01/app/dp_dir
total 4784
-rw-r-----. 1 oracle oinstall 4153344 Jan  6 06:02 full_exp.dmp
-rw-r--r--. 1 oracle oinstall   10847 Jan  6 06:02 full_exp.log
-rw-r-----. 1 oracle oinstall  724992 Jan  6 05:54 hr_exp.dmp
-rw-r--r--. 1 oracle oinstall    2403 Jan  6 05:54 hr_exp.log
[oracle@orcl19c ~]$ scp /u01/app/dp_dir/hr_exp.dmp oracle@26ai-single:/opt/oracle/dp_dir
The authenticity of host '26ai-single (26ai-single)' can't be established.
ECDSA key fingerprint is SHA256:qJ35kUixSm/Jn7VsEqCSG4gJk94/VJlFSYpjp3lraeM.
ECDSA key fingerprint is MD5:e2:77:28:4d:dd:11:ef:c7:c4:eb:e6:b6:46:41:66:9a.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '26ai-single' (ECDSA) to the list of known hosts.
oracle@26ai-single's password:
hr_exp.dmp                                                                                                                                                 100%  708KB  58.8MB/s   00:00
[oracle@orcl19c ~]$ scp /u01/app/dp_dir/full_exp.dmp oracle@26ai-single:/opt/oracle/dp_dir
oracle@26ai-single's password:
full_exp.dmp                                                                                                                                               100% 4056KB  11.4MB/s   00:00
[oracle@orcl19c ~]$

2. Import on Target (26ai Free)

Place the created .dmp file in the directory of the 26ai environment (e.g., /opt/oracle/admin/free/dpdump or wherever DATA_PUMP_DIR points).

Checking Directory Object on 26ai side

-- Connect to 26ai (PDB: freepdb1)
CONN system/oracle@26ai-single:1521/freepdb1
CREATE OR REPLACE DIRECTORY dp_dir AS '/opt/oracle/dp_dir'; -- Specify path according to environment
GRANT READ, WRITE ON DIRECTORY dp_dir TO system;

Case A: Import in Schema Mode

When migrating only specific application data (e.g., HR schema), it typically completes without errors.

impdp system/oracle@26ai-single:1521/freepdb1 schemas=hr directory=dp_dir dumpfile=hr_exp.dmp logfile=hr_imp.log

Result: The HR schema created in 19c is imported into the 26ai environment without issues. Since compatibility between versions is maintained, this method is basically recommended.

🖥️ Execution results using a real device

View execution results (click here)


[oracle@26ai-single ~]$ impdp system/oracle@26ai-single:1521/freepdb1 schemas=hr directory=dp_dir dumpfile=hr_exp.dmp logfile=hr_imp.log

Import: Release 23.26.0.0.0 - Production on Tue Jan 6 09:32:25 2026
Version 23.26.0.0.0

Copyright (c) 1982, 2025, Oracle and/or its affiliates.  All rights reserved.

Connected to: Oracle AI Database 26ai Free Release 23.26.0.0.0 - Develop, Learn, and Run for Free
Master table "SYSTEM"."SYS_IMPORT_SCHEMA_01" successfully loaded/unloaded
Starting "SYSTEM"."SYS_IMPORT_SCHEMA_01":  system/********@26ai-single:1521/freepdb1 schemas=hr directory=dp_dir dumpfile=hr_exp.dmp logfile=hr_imp.log
Processing object type SCHEMA_EXPORT/USER
Processing object type SCHEMA_EXPORT/SYSTEM_GRANT
Processing object type SCHEMA_EXPORT/ROLE_GRANT
Processing object type SCHEMA_EXPORT/DEFAULT_ROLE
Processing object type SCHEMA_EXPORT/TABLESPACE_QUOTA
Processing object type SCHEMA_EXPORT/SEQUENCE/SEQUENCE
Processing object type SCHEMA_EXPORT/TABLE/TABLE
Processing object type SCHEMA_EXPORT/TABLE/TABLE_DATA
. . imported "HR"."EMPLOYEES"                             17.1 KB     107 rows
. . imported "HR"."LOCATIONS"                              8.4 KB      23 rows
. . imported "HR"."JOB_HISTORY"                            7.2 KB      10 rows
. . imported "HR"."JOBS"                                   7.1 KB      19 rows
. . imported "HR"."DEPARTMENTS"                            7.1 KB      27 rows
. . imported "HR"."COUNTRIES"                              6.4 KB      25 rows
. . imported "HR"."REGIONS"                                5.5 KB       4 rows
Processing object type SCHEMA_EXPORT/TABLE/COMMENT
Processing object type SCHEMA_EXPORT/PROCEDURE/PROCEDURE
Processing object type SCHEMA_EXPORT/PROCEDURE/ALTER_PROCEDURE
Processing object type SCHEMA_EXPORT/VIEW/VIEW
Processing object type SCHEMA_EXPORT/TABLE/INDEX/INDEX
Processing object type SCHEMA_EXPORT/TABLE/CONSTRAINT/CONSTRAINT
Processing object type SCHEMA_EXPORT/TABLE/INDEX/STATISTICS/INDEX_STATISTICS
Processing object type SCHEMA_EXPORT/TABLE/CONSTRAINT/REF_CONSTRAINT
Processing object type SCHEMA_EXPORT/TABLE/TRIGGER
Processing object type SCHEMA_EXPORT/TABLE/STATISTICS/TABLE_STATISTICS
Job "SYSTEM"."SYS_IMPORT_SCHEMA_01" successfully completed at Tue Jan 6 09:33:51 2026 elapsed 0 00:01:18

[oracle@26ai-single ~]$ sqlplus hr/hr@26ai-single:1521/freepdb1

SQL*Plus: Release 23.26.0.0.0 - Production on Tue Jan 6 09:34:30 2026
Version 23.26.0.0.0

Copyright (c) 1982, 2025, Oracle.  All rights reserved.


Connected to:
Oracle AI Database 26ai Free Release 23.26.0.0.0 - Develop, Learn, and Run for Free
Version 23.26.0.0.0

SQL> show con_name

CON_NAME
------------------------------
FREEPDB1
SQL> select table_name from user_tables;

TABLE_NAME
--------------------------------------------------------------------------------
COUNTRIES
EMPLOYEES
REGIONS
LOCATIONS
JOBS
DEPARTMENTS
JOB_HISTORY

7 rows selected.

SQL> exit
Disconnected from Oracle AI Database 26ai Free Release 23.26.0.0.0 - Develop, Learn, and Run for Free
Version 23.26.0.0.0
[oracle@26ai-single ~]$

Case B: Import in Full Mode

When attempting to migrate the entire database, errors occur due to differences in system areas.

impdp system/oracle@26ai-single:1521/freepdb1 full=y directory=dp_dir dumpfile=full_exp.dmp logfile=full_imp.log

Result: The following group of errors occurred. These are “errors that can be ignored depending on migration requirements.” Details are explained in the next section.

🖥️ Execution results using a real device

View execution results (click here)


[oracle@26ai-single ~]$ impdp system/oracle@192.168.56.26:1521/freepdb1 full=y directory=dp_dir dumpfile=full_exp.dmp logfile=full_imp.log

Import: Release 23.26.0.0.0 - Production on Tue Jan 6 09:38:26 2026
Version 23.26.0.0.0

Copyright (c) 1982, 2025, Oracle and/or its affiliates.  All rights reserved.

Connected to: Oracle AI Database 26ai Free Release 23.26.0.0.0 - Develop, Learn, and Run for Free
Master table "SYSTEM"."SYS_IMPORT_FULL_01" successfully loaded/unloaded
Starting "SYSTEM"."SYS_IMPORT_FULL_01":  system/********@26ai-single:1521/freepdb1 full=y directory=dp_dir dumpfile=full_exp.dmp logfile=full_imp.log
Processing object type DATABASE_EXPORT/PRE_SYSTEM_IMPCALLOUT/MARKER/LABEL_SECURITY
Processing object type DATABASE_EXPORT/PRE_SYSTEM_IMPCALLOUT/MARKER/SEMANTIC
Processing object type DATABASE_EXPORT/PRE_SYSTEM_IMPCALLOUT/MARKER/SCHEDULER
Processing object type DATABASE_EXPORT/PRE_SYSTEM_IMPCALLOUT/MARKER/WMSYS
Processing object type DATABASE_EXPORT/PRE_SYSTEM_IMPCALLOUT/MARKER/DATAPUMP
Processing object type DATABASE_EXPORT/PRE_INSTANCE_IMPCALLOUT/MARKER/AUDIT_TRAILS
Processing object type DATABASE_EXPORT/PRE_INSTANCE_IMPCALLOUT/MARKER/DATAPUMP
Processing object type DATABASE_EXPORT/PRE_INSTANCE_IMPCALLOUT/MARKER/LABEL_SECURITY
Processing object type DATABASE_EXPORT/PRE_INSTANCE_IMPCALLOUT/MARKER/NETWORK_ACL
Processing object type DATABASE_EXPORT/PRE_INSTANCE_IMPCALLOUT/MARKER/PSTDY
Processing object type DATABASE_EXPORT/PRE_INSTANCE_IMPCALLOUT/MARKER/SCHEDULER
Processing object type DATABASE_EXPORT/PRE_INSTANCE_IMPCALLOUT/MARKER/SEMANTIC
Processing object type DATABASE_EXPORT/PRE_INSTANCE_IMPCALLOUT/MARKER/SMB
Processing object type DATABASE_EXPORT/PRE_INSTANCE_IMPCALLOUT/MARKER/SQL_FIREWALL
Processing object type DATABASE_EXPORT/PRE_INSTANCE_IMPCALLOUT/MARKER/TSDP
Processing object type DATABASE_EXPORT/PRE_INSTANCE_IMPCALLOUT/MARKER/WMSYS
Processing object type DATABASE_EXPORT/TABLESPACE
ORA-31684: Object type TABLESPACE:"UNDOTBS1" already exists

ORA-31684: Object type TABLESPACE:"TEMP" already exists

ORA-31684: Object type TABLESPACE:"USERS" already exists

Processing object type DATABASE_EXPORT/PROFILE
Processing object type DATABASE_EXPORT/SCHEMA/USER
Processing object type DATABASE_EXPORT/RADM_FPTM
ORA-39083: Object type PROC_SYSTEM_GRANT failed to create with error:
ORA-29393: user EM_EXPRESS_ALL does not exist or is not logged on

Failing sql is:
BEGIN
dbms_resource_manager_privs.grant_system_privilege(grantee_name => '"EM_EXPRESS_ALL"', admin_option => TRUE);COMMIT; END;

Processing object type DATABASE_EXPORT/SCHEMA/GRANT/SYSTEM_GRANT
Processing object type DATABASE_EXPORT/SCHEMA/ROLE_GRANT
ORA-39083: Object type ROLE_GRANT failed to create with error:
ORA-01917: user or role 'GSMROOTUSER' does not exist

Failing sql is:
 GRANT "GSMROOTUSER_ROLE" TO "GSMROOTUSER"

Processing object type DATABASE_EXPORT/SCHEMA/DEFAULT_ROLE
ORA-39083: Object type DEFAULT_ROLE:"GSMROOTUSER" failed to create with error:
ORA-01918: user 'GSMROOTUSER' does not exist

Failing sql is:
 ALTER USER "GSMROOTUSER" DEFAULT ROLE ALL

Processing object type DATABASE_EXPORT/SCHEMA/ON_USER_GRANT
ORA-39083: Object type ON_USER_GRANT failed to create with error:
ORA-31625: Schema GSMROOTUSER is needed to import this object, but is unaccessible
ORA-01435: user does not exist

Failing sql is:
 GRANT INHERIT PRIVILEGES ON USER "GSMROOTUSER" TO "PUBLIC"

Processing object type DATABASE_EXPORT/SCHEMA/TABLESPACE_QUOTA
Processing object type DATABASE_EXPORT/RESOURCE_COST
Processing object type DATABASE_EXPORT/TRUSTED_DB_LINK
Processing object type DATABASE_EXPORT/SCHEMA/SEQUENCE/SEQUENCE
Processing object type DATABASE_EXPORT/DIRECTORY/DIRECTORY
ORA-31684: Object type DIRECTORY:"DP_DIR" already exists

>>> Cannot set an SCN larger than the current SCN. If a Streams Capture configuration was imported then the Apply that processes the captured messages needs to be dropped and recreated. See My Oracle Support article number 1380295.1.
ORA-39083: Object type PROCACT_SCHEMA failed to create with error:
ORA-31625: Schema GSMROOTUSER is needed to import this object, but is unaccessible
ORA-01435: user does not exist

Failing sql is:
BEGIN
sys.dbms_logrep_imp.instantiate_schema(schema_name=>SYS_CONTEXT('USERENV','CURRENT_SCHEMA'), export_db_name=>'ORCL', inst_scn=>'2146750');COMMIT; END;

Processing object type DATABASE_EXPORT/EARLY_OPTIONS/VIEWS_AS_TABLES/TABLE
Processing object type DATABASE_EXPORT/EARLY_OPTIONS/VIEWS_AS_TABLES/TABLE_DATA
. . imported "SYS"."KU$_EXPORT_USER_MAP"                   6.1 KB      37 rows
Processing object type DATABASE_EXPORT/EARLY_POST_INSTANCE_IMPCALLOUT/MARKER/DATAPUMP
Processing object type DATABASE_EXPORT/NORMAL_OPTIONS/TABLE
Processing object type DATABASE_EXPORT/NORMAL_OPTIONS/TABLE_DATA
. . imported "SYSTEM"."REDO_DB_TMP"                       25.6 KB       1 rows
. . imported "WMSYS"."E$WORKSPACES_TABLE$"                12.1 KB       1 rows
. . imported "WMSYS"."E$HINT_TABLE$"                        10 KB      97 rows
. . imported "WMSYS"."E$WORKSPACE_PRIV_TABLE$"             7.1 KB      11 rows
. . imported "SYS"."AMGT$DP$DAM_CONFIG_PARAM$"             6.5 KB      14 rows
. . imported "SYS"."DP$TSDP_SUBPOL$"                       6.3 KB       1 rows
. . imported "WMSYS"."E$NEXTVER_TABLE$"                    6.4 KB       1 rows
. . imported "WMSYS"."E$ENV_VARS$"                           6 KB       3 rows
. . imported "SYS"."DP$TSDP_PARAMETER$"                      6 KB       1 rows
. . imported "SYS"."DP$TSDP_POLICY$"                       5.9 KB       1 rows
. . imported "WMSYS"."E$VERSION_HIERARCHY_TABLE$"            6 KB       1 rows
. . imported "WMSYS"."E$EVENTS_INFO$"                      5.8 KB      12 rows
. . imported "AUDSYS"."AMGT$DP$AUD$UNIFIED":"AUD_UNIFIED_P0"      0 KB       0 rows
. . imported "AUDSYS"."AMGT$DP$AUD$UNIFIED":"SYS_P181"   122.8 KB     148 rows
. . imported "AUDSYS"."AMGT$DP$AUD$UNIFIED":"SYS_P241"    59.5 KB      14 rows
. . imported "LBACSYS"."OLS_DP$OLS$AUDIT"                    0 KB       0 rows
. . imported "LBACSYS"."OLS_DP$OLS$COMPARTMENTS"             0 KB       0 rows
. . imported "LBACSYS"."OLS_DP$OLS$GROUPS"                   0 KB       0 rows
. . imported "LBACSYS"."OLS_DP$OLS$LAB"                      0 KB       0 rows
. . imported "LBACSYS"."OLS_DP$OLS$LEVELS"                   0 KB       0 rows
. . imported "LBACSYS"."OLS_DP$OLS$POL"                      0 KB       0 rows
. . imported "LBACSYS"."OLS_DP$OLS$POLS"                     0 KB       0 rows
. . imported "LBACSYS"."OLS_DP$OLS$POLT"                     0 KB       0 rows
. . imported "LBACSYS"."OLS_DP$OLS$PROFILE"                  0 KB       0 rows
. . imported "LBACSYS"."OLS_DP$OLS$PROG"                     0 KB       0 rows
. . imported "LBACSYS"."OLS_DP$OLS$USER"                     0 KB       0 rows
. . imported "SYS"."AMGT$DP$AUD$"                            0 KB       0 rows
. . imported "SYS"."AMGT$DP$DAM_CLEANUP_EVENTS$"             0 KB       0 rows
. . imported "SYS"."AMGT$DP$DAM_CLEANUP_JOBS$"               0 KB       0 rows
. . imported "SYS"."DP$TSDP_ASSOCIATION$"                    0 KB       0 rows
. . imported "SYS"."DP$TSDP_CONDITION$"                      0 KB       0 rows
. . imported "SYS"."DP$TSDP_FEATURE_POLICY$"                 0 KB       0 rows
. . imported "SYS"."DP$TSDP_PROTECTION$"                     0 KB       0 rows
. . imported "SYS"."DP$TSDP_SENSITIVE_DATA$"                 0 KB       0 rows
. . imported "SYS"."DP$TSDP_SENSITIVE_TYPE$"                 0 KB       0 rows
. . imported "SYS"."DP$TSDP_SOURCE$"                         0 KB       0 rows
. . imported "SYSTEM"."REDO_LOG_TMP"                         0 KB       0 rows
. . imported "WMSYS"."E$BATCH_COMPRESSIBLE_TABLES$"          0 KB       0 rows
. . imported "WMSYS"."E$CONSTRAINTS_TABLE$"                  0 KB       0 rows
. . imported "WMSYS"."E$CONS_COLUMNS$"                       0 KB       0 rows
. . imported "WMSYS"."E$LOCKROWS_INFO$"                      0 KB       0 rows
. . imported "WMSYS"."E$MODIFIED_TABLES$"                    0 KB       0 rows
. . imported "WMSYS"."E$MP_GRAPH_WORKSPACES_TABLE$"          0 KB       0 rows
. . imported "WMSYS"."E$MP_PARENT_WORKSPACES_TABLE$"         0 KB       0 rows
. . imported "WMSYS"."E$NESTED_COLUMNS_TABLE$"               0 KB       0 rows
. . imported "WMSYS"."E$RESOLVE_WORKSPACES_TABLE$"           0 KB       0 rows
. . imported "WMSYS"."E$RIC_LOCKING_TABLE$"                  0 KB       0 rows
. . imported "WMSYS"."E$RIC_TABLE$"                          0 KB       0 rows
. . imported "WMSYS"."E$RIC_TRIGGERS_TABLE$"                 0 KB       0 rows
. . imported "WMSYS"."E$UDTRIG_DISPATCH_PROCS$"              0 KB       0 rows
. . imported "WMSYS"."E$UDTRIG_INFO$"                        0 KB       0 rows
. . imported "WMSYS"."E$VERSION_TABLE$"                      0 KB       0 rows
. . imported "WMSYS"."E$VT_ERRORS_TABLE$"                    0 KB       0 rows
. . imported "WMSYS"."E$WORKSPACE_SAVEPOINTS_TABLE$"         0 KB       0 rows
Processing object type DATABASE_EXPORT/NORMAL_OPTIONS/VIEWS_AS_TABLES/TABLE
Processing object type DATABASE_EXPORT/NORMAL_OPTIONS/VIEWS_AS_TABLES/TABLE_DATA
. . imported "MDSYS"."RDF_PARAM$TBL"                       6.5 KB       3 rows
. . imported "SYS"."AMGT$DP$AUDTAB$TBS$FOR_EXPORT"           6 KB       2 rows
. . imported "SYS"."DP$DBA_SENSITIVE_DATA"                   0 KB       0 rows
. . imported "SYS"."DP$DBA_TSDP_POLICY_PROTECTION"           0 KB       0 rows
. . imported "SYS"."AMGT$DP$FGA_LOG$FOR_EXPORT"              0 KB       0 rows
. . imported "SYS"."NACL$_ACE_IMP"                           0 KB       0 rows
. . imported "SYS"."NACL$_HOST_IMP"                          7 KB       2 rows
. . imported "SYS"."NACL$_WALLET_IMP"                        0 KB       0 rows
. . imported "SYS"."DATAPUMP$SQL$TEXT"                       0 KB       0 rows
. . imported "SYS"."DATAPUMP$SQL$"                           0 KB       0 rows
. . imported "SYS"."DATAPUMP$SQLOBJ$AUXDATA"                 0 KB       0 rows
. . imported "SYS"."DATAPUMP$SQLOBJ$DATA"                    0 KB       0 rows
. . imported "SYS"."DATAPUMP$SQLOBJ$PLAN"                    0 KB       0 rows
. . imported "SYS"."DATAPUMP$SQLOBJ$"                        0 KB       0 rows
. . imported "WMSYS"."E$EXP_MAP"                           7.7 KB       3 rows
. . imported "WMSYS"."E$METADATA_MAP"                        0 KB       0 rows
Processing object type DATABASE_EXPORT/NORMAL_POST_INSTANCE_IMPCALLOUT/MARKER/AUDIT_TRAILS
Processing object type DATABASE_EXPORT/NORMAL_POST_INSTANCE_IMPCALLOUT/MARKER/LABEL_SECURITY
Processing object type DATABASE_EXPORT/NORMAL_POST_INSTANCE_IMPCALLOUT/MARKER/NETWORK_ACL
Processing object type DATABASE_EXPORT/NORMAL_POST_INSTANCE_IMPCALLOUT/MARKER/PSTDY
Processing object type DATABASE_EXPORT/NORMAL_POST_INSTANCE_IMPCALLOUT/MARKER/SCHEDULER
Processing object type DATABASE_EXPORT/NORMAL_POST_INSTANCE_IMPCALLOUT/MARKER/SEMANTIC
Processing object type DATABASE_EXPORT/NORMAL_POST_INSTANCE_IMPCALLOUT/MARKER/SMB
Processing object type DATABASE_EXPORT/NORMAL_POST_INSTANCE_IMPCALLOUT/MARKER/SQL_FIREWALL
Processing object type DATABASE_EXPORT/NORMAL_POST_INSTANCE_IMPCALLOUT/MARKER/TSDP
Processing object type DATABASE_EXPORT/NORMAL_POST_INSTANCE_IMPCALLOUT/MARKER/WMSYS
Processing object type DATABASE_EXPORT/SCHEMA/TABLE/TABLE
Processing object type DATABASE_EXPORT/SCHEMA/TABLE/TABLE_DATA
. . imported "HR"."EMPLOYEES"                             17.1 KB     107 rows
. . imported "HR"."LOCATIONS"                              8.4 KB      23 rows
. . imported "HR"."JOB_HISTORY"                            7.2 KB      10 rows
. . imported "HR"."JOBS"                                   7.1 KB      19 rows
. . imported "HR"."DEPARTMENTS"                            7.1 KB      27 rows
. . imported "HR"."COUNTRIES"                              6.4 KB      25 rows
. . imported "HR"."REGIONS"                                5.5 KB       4 rows
Processing object type DATABASE_EXPORT/SCHEMA/TABLE/COMMENT
Processing object type DATABASE_EXPORT/SCHEMA/PROCEDURE/PROCEDURE
Processing object type DATABASE_EXPORT/SCHEMA/PROCEDURE/ALTER_PROCEDURE
Processing object type DATABASE_EXPORT/SCHEMA/VIEW/VIEW
Processing object type DATABASE_EXPORT/SCHEMA/TABLE/INDEX/INDEX
Processing object type DATABASE_EXPORT/SCHEMA/TABLE/CONSTRAINT/CONSTRAINT
Processing object type DATABASE_EXPORT/SCHEMA/TABLE/INDEX/STATISTICS/INDEX_STATISTICS
Processing object type DATABASE_EXPORT/SCHEMA/TABLE/CONSTRAINT/REF_CONSTRAINT
Processing object type DATABASE_EXPORT/SCHEMA/TABLE/STATISTICS/TABLE_STATISTICS
Processing object type DATABASE_EXPORT/SCHEMA/TABLE/TRIGGER
Processing object type DATABASE_EXPORT/FINAL_POST_INSTANCE_IMPCALLOUT/MARKER/AUDIT_TRAILS
Processing object type DATABASE_EXPORT/FINAL_POST_INSTANCE_IMPCALLOUT/MARKER/DATAPUMP
Processing object type DATABASE_EXPORT/FINAL_POST_INSTANCE_IMPCALLOUT/MARKER/LABEL_SECURITY
Processing object type DATABASE_EXPORT/FINAL_POST_INSTANCE_IMPCALLOUT/MARKER/NETWORK_ACL
Processing object type DATABASE_EXPORT/FINAL_POST_INSTANCE_IMPCALLOUT/MARKER/PSTDY
Processing object type DATABASE_EXPORT/FINAL_POST_INSTANCE_IMPCALLOUT/MARKER/SCHEDULER
Processing object type DATABASE_EXPORT/FINAL_POST_INSTANCE_IMPCALLOUT/MARKER/SEMANTIC
Processing object type DATABASE_EXPORT/FINAL_POST_INSTANCE_IMPCALLOUT/MARKER/SMB
Processing object type DATABASE_EXPORT/FINAL_POST_INSTANCE_IMPCALLOUT/MARKER/SQL_FIREWALL
Processing object type DATABASE_EXPORT/FINAL_POST_INSTANCE_IMPCALLOUT/MARKER/TSDP
Processing object type DATABASE_EXPORT/FINAL_POST_INSTANCE_IMPCALLOUT/MARKER/WMSYS
Processing object type DATABASE_EXPORT/AUDIT_UNIFIED/AUDIT_POLICY_ENABLE
Processing object type DATABASE_EXPORT/POST_SYSTEM_IMPCALLOUT/MARKER/LABEL_SECURITY
Processing object type DATABASE_EXPORT/POST_SYSTEM_IMPCALLOUT/MARKER/SEMANTIC
Processing object type DATABASE_EXPORT/POST_SYSTEM_IMPCALLOUT/MARKER/SCHEDULER
Processing object type DATABASE_EXPORT/POST_SYSTEM_IMPCALLOUT/MARKER/WMSYS
Processing object type DATABASE_EXPORT/POST_SYSTEM_IMPCALLOUT/MARKER/DATAPUMP
Job "SYSTEM"."SYS_IMPORT_FULL_01" completed with 9 error(s) at Tue Jan 6 09:44:29 2026 elapsed 0 00:05:57

[oracle@26ai-single ~]$ sqlplus hr/hr@26ai-single:1521/freepdb1

SQL*Plus: Release 23.26.0.0.0 - Production on Tue Jan 6 09:46:12 2026
Version 23.26.0.0.0

Copyright (c) 1982, 2025, Oracle.  All rights reserved.


Connected to:
Oracle AI Database 26ai Free Release 23.26.0.0.0 - Develop, Learn, and Run for Free
Version 23.26.0.0.0

SQL> select table_name from user_tables;

TABLE_NAME
--------------------------------------------------------------------------------
COUNTRIES
EMPLOYEES
REGIONS
LOCATIONS
JOBS
DEPARTMENTS
JOB_HISTORY

7 rows selected.

Error Analysis and Countermeasures for Full Import

We have summarized the main error logs generated during a full import from 19c to 26ai Free, their causes, and how to handle them.

Error Code	Target Object	Cause / Explanation	Countermeasure Judgment
ORA-31684	TABLESPACE (UNDOTBS1, TEMP, USERS) DIRECTORY (DP_DIR)	“Already exists” error. Occurs when attempting to recreate tablespaces or directories that exist by default when the 26ai environment is created.	Ignore OK
ORA-29393 ORA-39083	USER (EM_EXPRESS_ALL)	“User does not exist” error. Failure to grant privileges to system users (like EM Express related) that do not exist (or are unnecessary) on the 26ai side due to version or configuration differences.	Ignore OK (If not needed for App)
ORA-01917 ORA-01918	ROLE/USER (GSMROOTUSER)	“GSM (Global Data Services) related”. Occurs because GSM-related roles or users included in the 19c environment do not fit the 26ai Free PDB environment or prerequisites differ.	Ignore OK (If GSM is unused)
ORA-31625 ORA-01435	PROCACT_SCHEMA(dbms_logrep_imp)	“Replication/Streams related”. Occurs because dependent system users do not exist while attempting to migrate internal system replication settings.	Ignore OK

Explanation: Why Do Errors Occur?

Oracle Database optimizes and changes internal system users (accounts other than SYS or SYSTEM) and role configurations with every version upgrade. When exporting with full=y, all these “old version system definitions” are also output. However, the new version (26ai) rejects them due to reasons such as “that user is no longer needed,” “it is locked from the start,” or “the name has changed,” resulting in errors.

If the application data (in this example, tables and data of the HR schema) is imported correctly, these system-related errors do not affect the success of the migration. Even if the end of the log says Job … completed with 9 error(s), do not panic and check the contents of the log.

Note: Since verifying whether errors are safe to ignore is difficult, migration in Schema Mode is basically recommended.

Troubleshooting

Q. ORA-28040: No matching authentication protocol appears during import

Cause: Mismatch in SQLNET.ALLOWED_LOGON_VERSION between the client (impdp source) and the server.
Action: Check sqlnet.ora on the source or use a compatible client version.

Q. There are tables with no data

Cause: Due to the “Deferred Segment Creation” feature in 19c and later, extents for empty tables may not have been allocated, causing them to be excluded from the export.
Action: Execute ALTER TABLE ... ALLOCATE EXTENT; on the 19c side, or adjust the VERSION parameter during export and retry.

Notes on Operation, Monitoring, and Security

Handling Password Files: Specifying expdp system/password... on the command line poses a security risk. In a production environment, it is recommended to use a parfile (parameter file) and operate without including passwords.
Limitations of 26ai Free: 26ai Free has limitations on data volume (maximum 12GB user data) and memory usage. When migrating large-scale data from 19c Enterprise Edition, it is necessary to verify beforehand that these limits are not exceeded.
Operational Differences between Free and Official (Production) Versions: The 26ai Free verified in this article is a developer release. The future production releases (Enterprise Edition / Standard Edition 2) may differ in default initialization parameters and the behavior of some features, in addition to resource limitations. When planning a migration to a commercial environment, always perform verification in an official version environment.
Recommended Migration Flow: To avoid troubles caused by version differences, it is safest to specify required schemas like schemas=HR, APP_USER for import, rather than full=y.

FAQ

Q1: Is direct Data Pump migration from 19c to 26ai supported?

A1: Yes, Data Pump dump files have high backward compatibility and can be read. However, objects related to deprecated or removed features may result in errors.

Q2: Is there a way to eliminate ORA-31684 (Already exists)?

A2: By adding parameters like EXCLUDE=TABLESPACE,DIRECTORY to impdp, you can specify skipping the creation of existing objects and suppress error logs.

Q3: How can I shorten the time required for import?

A3: While the PARALLEL option is effective in Enterprise Edition, 26ai Free has a CPU limit (2 CPU threads), so the effect of parallelism is limited. Measures such as suppressing unnecessary log output or postponing index creation are effective.

Summary

Compatibility is Good: Dumps acquired in 19c can be read in 26ai Free without problems.
Schema Mode Recommended: Migrate using schemas= specification as much as possible to avoid unnecessary system errors.
Scrutinize Full Import Errors: ORA-31684 (Existing) and ORA-39083 (System Privileges/Users) can be ignored in most cases.
Understand Characteristics of Free Version: 26ai Free may behave differently from the official version, so caution is needed for verification before production migration.

The latest Oracle Database 26ai is packed with attractive features like AI Vector Search. Easily migrate data from your existing 19c environment and try out the new features.

This article explains based on Oracle Database 19c and Oracle Database 26ai Free (behavior may differ for other versions or production releases).

[reference]
Oracle Data Pump Import