guide to fixing ora 00600 4137 and ora 00600-4193 caused by corrupted undo tablespace without backup

troubleshooting database Hits: 68

One of the most challenging and critical scenarios for an Oracle DBA is encountering Oracle internal errors known as ORA-00600 during the database OPEN phase. This situation becomes far more complicated when the database is in a test/development environment or lacks valid backups and archived redo logs, making standard Media Recovery impossible.

In this article, we delve into the root cause of the simultaneous occurrence of ORA-00600 [4137] and ORA-00600 [4193] errors and provide a practical methodology to bypass incomplete recovery, successfully open the database, and completely rebuild the Undo tablespace.

Critical Warning: Risk of Data Loss and Method Limitations

The method used in this scenario is an emergency/bypass solution to rescue and open the database in critical conditions—especially when no backups or archive logs are available and the database crashes during the OPEN stage due to Undo corruption.

Why is there a risk of Data Loss?

Under normal conditions, Oracle's Crash Recovery must:

  • Apply committed changes using Redo (Roll Forward)
  • And rollback uncommitted transactions using Undo (Rollback)

However, in this scenario:

  • The Undo Tablespace was corrupted, making the rollback of certain transactions impossible.
  • By using emergency parameters (such as undo_management=MANUAL and event 10513), part of the Transaction Recovery/Rollback process was bypassed to allow the database to OPEN.

 

1. Root Cause Analysis

Symptoms and Error Logs

When attempting to open the database, the following errors are logged in the alert.log or SMON process trace files:

Errors in file /u01/app/oracle/diag/rdbms/.../MKCFSTESTDB_smon_32888.trc:
ORA-00600: internal error code, arguments: [4137], [1], [23], [], [], []
ORA-00600: internal error code, arguments: [4193], [], [], []
ORA-00604: error occurred at recursive SQL level 1
ORA-00607: Internal error occurred during recovery action

Why does this happen?

  1. Crash Recovery Mechanism: When the database crashes or shuts down abnormally, Oracle identifies uncommitted transactions during startup via the SMON process and initiates a Rollback operation to return the system to a consistent state.
  2. Error ORA-00600 [4137]: Indicates the inability to read or find the corresponding blocks for a transaction in the Undo segment (e.g., transaction (1, 23)).
  3. Error ORA-00600 [4193]: Indicates a structural mismatch (Sequence/Block Header Mismatch) between the Redo records and Undo block headers.
  4. Consequence: For data safety and to prevent further block corruption, Oracle immediately forces a SHUTDOWN ABORT, preventing the database from reaching the OPEN state.

2. Bypass & Rebuild Strategy

If an RMAN backup is available, the primary and standard approach is RESTORE / RECOVER DATAFILE. However, in non-production environments or when no backups exist, the operational roadmap consists of 3 main phases:

  1. Temporarily disable SMON transaction recovery and set the Undo management mode to MANUAL.
  2. Open the database (OPEN) and create a brand-new, healthy Undo Tablespace.
  3. Permanently switch to the new Undo tablespace, remove emergency parameters, and return the system to normal (AUTO) mode.

3. Step-by-Step Implementation

Step 0: Take an OS-Level Cold Backup

Before making any modifications, copy all Oracle database files to a secure location to prevent further disk-level data loss risk.

Step 1: Create a PFILE and Configure Emergency Parameters

First, connect as SYSDBA, start the database in MOUNT mode, and create a text-based PFILE from the SPFILE:

sqlplus / as sysdba
SQL> startup mount;
SQL> create pfile='/tmp/initMKCFSTESTDB.ora' from spfile;
SQL> shutdown abort;

Next, open /tmp/initMKCFSTESTDB.ora in a text editor and add/modify the following parameters:

*.undo_management='MANUAL'

*.event="10513 trace name context forever, level 2"

# Offline corrupted undo segments (if needed)
*._offline_rollback_segments=(_SYSSMU1$, _SYSSMU2$, _SYSSMU3$, _SYSSMU4$, _SYSSMU5$, _SYSSMU6$, _SYSSMU7$, _SYSSMU8$, _SYSSMU9$, _SYSSMU10$)

 

Step 2: Open Database and Create a New Undo Tablespace

Now, open the database using the customized PFILE:

SQL> startup pfile='/tmp/initMKCFSTESTDB.ora';

Immediately create a brand-new Undo Tablespace:

SQL> create undo tablespace UNDOTBS2 
     datafile '/u01/app/oradata/MKCFSTESTDB/undotbs02.dbf' size 4G 
     autoextend on next 256M maxsize unlimited;

Important Note: If you execute ALTER SYSTEM SET UNDO_TABLESPACE=UNDOTBS2; at this stage, you will encounter the following error:

ORA-30014: operation only supported in Automatic Undo Management mode

This error is completely normal because the database was opened in MANUAL mode; therefore, switching undo tablespaces must be done via the parameter file.

Step 3: Return to Automatic (AUTO) Mode and Persist Configuration

Shut down the database:

SQL> shutdown immediate;

-- If it hangs: shutdown abort;

Open /tmp/initMKCFSTESTDB.ora again and configure parameters for normal operation:

  1. Change undo_management back to AUTO.
  2. Set undo_tablespace to UNDOTBS2.
  3. Remove or comment out (#) all lines related to event 10513 and hidden parameters (_offline...).

 

*.undo_management='AUTO'
*.undo_tablespace='UNDOTBS2'
# event="10513 trace name context forever, level 2"
# _offline_rollback_segments=...

 

Then, start the database with the modified PFILE and rebuild the official SPFILE:

SQL> startup pfile='/tmp/initMKCFSTESTDB.ora';
SQL> create spfile from pfile='/tmp/initMKCFSTESTDB.ora';

Step 4: Standard Startup and Dropping the Corrupted Undo Tablespace

Shut down the database and start it normally to ensure it uses the newly created SPFILE:

SQL> shutdown immediate;
SQL> startup;

 

Verify parameter configuration and confirm the active undo tablespace:

 

SQL> show parameter undo;

NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
undo_management string AUTO
undo_tablespace string UNDOTBS2

 

Check the status of the old segments and then drop the old corrupted tablespace along with its datafiles:

SQL> select tablespace_name, status, count(*) 
     from dba_rollback_segs 
     group by tablespace_name, status;

SQL> drop tablespace UNDOTBS1 including contents and datafiles;

4. Key Takeaways & Best Practices

  1. Purpose of Event 10513: This internal event instructs the Oracle kernel to suppress transaction recovery by SMON, allowing database access and troubleshooting.
  2. Never Leave Temporary Parameters: Always remove internal events (Events) and hidden parameters (underscore parameters) from your SPFILE after resolving the incident to ensure Oracle behaves predictably.
  3. Status of Unfinished Transactions: By bypassing corrupted Undo, transactions that were uncommitted at the time of the crash remain half-baked in table blocks. It is strongly recommended to perform logical consistency checks (Application-level Data Integrity Check) across operational tables after recovery.