Wednesday , May 29 2024

Correction of Corrupted UNDO tablespace.


If the Oracle UNDO table space is corrupted, it may be possible to get the error as follows.

ORA-00376: file string cannot be read at this time


When UNDO segments corrupted, the following should be done:

  • The undo_management parameter must be MANUAL.
  • A new UNDO tablespace must be created.
  • The problematic UNDO tablespace should be removed.
  • The undo_tablespace parameter must be modified to be the newly created UNDO tablespace.


Correction of corrupted UNDO tablespace step by step:

1- Identify the corrupted segments. The following query can be used to detect these segments.


2. Close the database.
3- You must change the corresponding pfile’s undo_management parameter to MANUAL and Change the value of the “_offline_rollback_segments” hidden parameter to be problematic segments.

Rows to add to the Pfile file:


# If there is one corrupted segment:


# If there is more than one corrupted segment:


4- Open the database in MOUNT mode and with RESTRICT.


5- Remove all corrupted segments and undo tablespace.

Rollback segment dropped.


Tablespace dropped.


6- Create new undo tablespace.


7- Close the database.


8- Delete the line _OFFLINE_ROLLBACK_SEGMENTS from the rows added in the Pfile, and UNDO_MANAGEMENT = AUTO.

If the name of the newly created undo tablespace is different from the deleted one, change it to undo_tablespace = <NEW_UNDOTBS1>.


9. Open the database normally from the pfile.


If you need to use Spfile after opening you can create the spfile with the help of the following script;


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One comment

  1. Thank you so much for these very clear instructions. I am a software developer, not a DBA, with a personal Oracle XE database containing more than 1.5 million horse racing records which are used for statistical analysis. The DB incurred a power outage during an update of the records, causing corruption of the undo tablespace. After struggling to understand and fix this problem, I found your excellent guidance. Thanks again, and yes I will get a new UPS backup to avoid this problem in the future.

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