Snapshot backup fails to complete


I have attempted to create a backup using Snapshot Pro in preparation to migrate the site to a new host, however, Snapshot has failed to complete.

I was able to backup the databases in a separate Snapshot but backing up files seems to hang at 'media'. I excluded 'media' in a separate backup and that also completed successfully. The attempts to snapshot the 'media' files result in the error messages: "Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator at to inform them of the time this error occurred, and the actions you performed just before this error.
More information about this error may be available in the server error log.
Additionally, a 500 Internal Server Error error was encountered while trying to use an ErrorDocument to handle the request."

I'm not sure if I'm doing something wrong or something isn't configured correctly. I've granted support access to the site and any insight as to how to fix this issue would be greatly appreciated.

Best regards

  • Predrag Dubajic

    Hey Ken,

    Hope you're doing well today :slight_smile:

    Can you tell me what is the size of your wp-content/uploads/ folder and what's the largest folder in there?
    It's possible that server can't handle the request if the folder are really big and that's why it fails.

    500 error on it's own doesn't tell us much so can you enable debug log in your wp-config.php by replacing define('WP_DEBUG', false); with this code:

    // Enable WP_DEBUG mode
    define('WP_DEBUG', true);
    // Enable Debug logging to the /wp-content/debug.log file
    define('WP_DEBUG_LOG', true);
    // Disable display of errors and warnings
    define('WP_DEBUG_DISPLAY', false);
    @ini_set( 'display_errors', 0 );

    After 500 shows again it should also create debug.log file in your wp-content folder that could tell us what is going on.
    Can you please save it as .txt file and attach it here so we can check it out.

    Could you also try changing zip method in Snapshots > Settings and see if that makes any difference since those two methods can behave differently depending on server configuration.

    Best regards,

  • Kenneth

    Hi Predrag,

    Sorry for the delay, I hope you're well.
    I have enabled error logging. I noted that there is a huge (41.78MB) error log file generated May 10 on the server.

    The uploads folder is quite large and the last media files backup was 360MB

    Changing the ZIP method didn't seem to help but it did generate some different errors.
    I received this error message when attempting a full site snapshot using PcLZIP:
    ERROR: PcLZIP file:media/2016/03 add failed -10: Unable to find End of Central Dir Record signature [code -10]
    ... and this when attempting a snapshot of media only:
    ERROR: PcLZIP file:media/2014/11 add failed -10: gzip temporary file '/home/grottyya/public_html/wp-content/uploads/snapshots/_backup/1463995747/pclzip-57457d04be9fd.gz' has invalid filesize - should be minimum 18 bytes [code -10]

    If it turns out that the folder is simply too large to generate a snapshot, would I be able to migrate the site to a new server using snapshots without the media and then ftp the media files across?

    Thanks again for your help.

    Best regards

  • Milan

    Hey Ken,

    Hope you are well today and thanks for waiting till now. :slight_smile:

    Our developer checked your site and want to know about your hosting provider, so could you please let us know where you are hosting your site. According to developer, this is happening due to something at hosting server side.

    Please let us know which service you are using as your hosting provider.

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