Wednesday, 29 April 2015

How to fix Exchange Error -501 (0xfffffe0b) JET_errLogFileCorrupt

Log files are the most critical component of Exchange server, as they play a significant role in recovery of Exchange when database is in shutdown stage. All Exchange admin’s are aware of the fact that even small errors in Log files may lead to serious problems such as Unable to Mount Stores, Exchange Server shutdown. One such error is JET_errLogFileCorrupt – which is faced due to log files corruption and may lead to Exchange corruption if not properly handled. Let’s check what this error is and how to tackle this.

What is Exchange Exchange Error - JET_errLogFileCorrupt ?

When user is unable to mount information store database due to the corrupt log file, there Exchange Error JET_errLogFileCorrupt is displayed.  Improper handling of this error may lead to inconsistent stage of database. For handling inconsistent stage you may need to use either eseutil.exe or any professional Exchange Recovery software. Here some common causes, resolution techniques, manual as well as professional discussed in this article.

Cause of this error: Corruption in log files is the main reason behind this error. Lost, damaged files or because of corruption in header of log files this error may be shown. After this error user gets unable to mount data to the database.

How to check your Log files are damaged?

To confirm that your log files are damaged or not. Follow certain steps:

1. Open command Prompt window
2. Change to the folder where the log files are located.
3. Type command: eseutil /ml Enn

If this process terminates with error -501 it means, it means your Log files are corrupt

Operation terminated with error -501 (JET_errLogFileCorrupt, Log file is corrupt)

Than you may need to resolve this error by following procedure mentioned below.

How to Resolve this Manually

To resolve this error manually, at first you need to remove your damaged log files from database and then restore them back, from the backup. After that you need to execute eseutil.exe to regenerate log files.

Here some steps had been discussed which could be followed to resolve this error.

1.  Try to locate a copy of Log files
2.  Discard the damaged log file
3. Restore backup of the Exchange database
4.  Perform Hard Recovery

Try to locate a copy of Log files: As a first solution, try to find a copy of Log files in working condition from Exchange online backup or from previous server backup. However if you are not having backup you may need to repair corrupt Log files using Hard recovery by Eseutility or by professional software for Exchange recocery.

Discard the damaged log file: If you find a copy of Log files in working condition, it means you can delete previous corrupt log files and restore them from backup but before that you need to discard damaged log files.

Restore backup of the Exchange database: After deleting corrupt Log files, now it’s time to restore Exchange database from backup. But if you having old copy of the database in that case you will lose all the data saved after creating backup, an alternate solution is to try to remove corruption using hard recovery.

Doing Hard Recovery for Log File repair: After restoring data from online backup, you may need to perform hard recovery to repair damaged log files. But before performing hard recovery it is advised to take a backup of the folder containing log files as data may be lost during this process.

1. Once restoration of the database is complete a file names ‘restore.env’ will be created at temporary folder ‘C:\Temp’. This will contain all logs that were backed up without being committed to the database.
2. After that execute command Eseutil /cc “Path of the restore.env containing folder”.
3. After complete execution of this command restore.env file will be deleted.

However it is extremely difficult to perform Hard recovery and to replay damaged log file into a database as along-with matching up databases and logs by signatures user may also need to keep record of checkpoint value in the database header, risk of replaying wrong log files into the database is also there. So rather than going for this complex process, it is advised to use a professional Exchange Recovery solution for solving this Error.

Using professional solution: As this solution of Eseutility may not work for you all the time. In case backup of exchange database is not there this solution will not work .There you may need to take help of professional Exchange recovery software which can thoroughly scan your damaged database and repair corrupt edb files providing access to Exchange data again.


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