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Fix "Fat Table Not Found" and "could not locate channel" backup job log errors

Getting "fat table not found" or "could not locate channel" errors in your backup logs? This usually means your backup storage is full or corrupted backup files need to be cleaned up.

What This Error Means

When you see these errors in your backup log:

  • "fat table not found, invalid document"
  • "fct: could not locate channel in"

It means NovaBACKUP found damaged or incomplete backup files, usually because:

  • Your backup drive ran out of space (most common cause)
  • The backup was interrupted during writing
  • Hardware issues with your storage device

Quick Fixes (Try These First!)

Step 1: Check Your Storage Space

This fixes 80% of these errors!

  1. Find your backup location:

    • Open NovaBACKUP
    • Go to Device tab
    • Click Properties on your backup device, to see the folder path value there (as a local path or a network path). Note: Only unmanaged 'Local Backup' devices can have their Properties viewed via the client GUI. If the "Properties" button is grayed out for that device in the "Device" tab after you did select your backup device, that is due to that device is a "Managed" 'Local Backup' device, that was created via the CMon UI, so in that case you can use the CMon web UI to view the Properties of that backup device there (in the "Agent > Devices" tab).

  2. Check available space:

    • Open Windows Explorer
    • Navigate to the backup drive letter that the backup job utilizes (that would be for a local drive, but if it is a network based 'Local Backup' device, that utilizes a network folder, you may need to use the NAS to check the free space value, or you can map a network drive letter to that same network share and check the free space value in Windows).
    • Right-click on the drive letter and select Properties
    • Look at "Free space" value there

  3. If space is low:

    • Free up space on the drive, for data that is outside of the backup folder, OR
    • Decrease retention settings in your backup job to keep fewer backups

Step 2: Update NovaBACKUP

Make sure you're running NovaBACKUP version 21.2 or newer, as these versions handle corrupted files better.

Step 3: Run the Backup Again

After freeing up space, try running your backup job again. The newer versions can often fix minor file corruption automatically.

If Simple Fixes Don't Work

Advanced Solution: Remove Corrupted Files

⚠️ Important: This involves deleting backup files. While safe when done correctly, please follow the steps exactly.

Step 1: Find the Problem Files

  1. Open your backup log:

    • In NovaBACKUP, go to Logs tab
    • Find the failed backup job
    • Look for error messages like:
    fat table not found, invalid document datafile://patch/(filename)

  2. Write down the filename:

    • Copy everything after "datafile://patch/"
    • Example: twfuzhkncybiewjyawqgqmfja3vw)_dev20250203151330991)sn20250426020001836
    • Add .dat to the end: twfuzhkncybiewjyawqgqmfja3vw)_dev20250203151330991)sn20250426020001836.dat

Step 2: Navigate to Backup Files

  1. Go to your backup device folder (from Step 1 above)
  2. Navigate deeper into the folder structure:
    • Look for: data\Appl NBK\Node NBK\
    • This is where the actual backup files (.dat files) are stored

Step 3: Remove Corrupted Files

  1. Find the specific file you wrote down in Step 1
  2. Enable file extensions in Windows Explorer:
    • Click View tab
    • Check "File name extensions"
  3. Delete ONLY the corrupted file(s) mentioned in your error log
    • ⚠️ Do NOT delete all .dat files - only the ones mentioned in the error

Step 4: Test the Fix

  1. Run your backup job again
  2. Check the log for errors
  3. If you see new "fat table" errors:
    • Repeat steps 1-3 for any new problematic files
    • This might take 2-3 attempts to clear all corrupted files

Step 5: Final Test

Run your backup one more time to confirm everything is working properly.

What to Expect After the Fix

Normal Behavior

After removing corrupted files, you might see this warning in your next backup log:

wrn*0x0000:4001*dlt: regenerating signatures, full copies will be stored

This is normal! It means:

  • NovaBACKUP is creating a fresh full backup
  • Future backups will be incremental as usual
  • Your backup schedule will work normally going forward

Success Signs

  • Backup completes without "fat table" errors
  • Backup log shows "Success" status (not "Warning" or "Failed")
  • Files are being backed up normally

Prevention Tips

Keep Your Storage Healthy

  • Monitor disk space regularly
  • Set up storage alerts if your system supports them
  • Clean up old backups periodically

Optimize Retention Settings

  • Reduce retention period if space is tight
  • Use incremental backups instead of multiple full backups
  • Consider cloud storage for unlimited space

Regular Maintenance

  • Run backup jobs regularly (don't let them sit idle for weeks)
  • Check backup logs occasionally for early warning signs
  • Update NovaBACKUP when new versions are available

When to Contact Support

Contact support if:

  • Simple fixes don't work and you're still getting errors
  • You're uncomfortable deleting backup files manually
  • Multiple backup jobs are showing the same errors
  • Hardware issues are suspected (failing drives, network problems)

Information to Provide

When contacting support, include:

  • Your NovaBACKUP version
  • Type of backup device (local drive, NAS, etc.)
  • Available storage space
  • Complete error messages from the backup log

Summary

Most "fat table not found" errors are caused by full storage drives.

Quick fix: Check your backup drive space and free up room.

If that doesn't work: Use the advanced steps to remove corrupted backup files, but follow the instructions carefully.

Prevention: Monitor storage space and keep your backup drives from getting too full.