The error message "500 SB_Facade_Exception_NotFound" in Plesk indicates that there may be an issue with accessing the Domains tab, possibly due to a missing or corrupted file or configuration.

Here are steps you can take to troubleshoot and potentially resolve the issue:

1. Check for Recent Changes:

   • Consider if any recent changes, updates, or modifications were made to your Plesk environment. Reverting any recent changes might help if the issue was caused by a recent action.

2. Restart Plesk Services:

   • Try restarting the Plesk services to see if it resolves the issue. You can do this via the Plesk interface or through the command line.

3. Check Disk Space:

   • Ensure that there is sufficient disk space available on your server. Running out of disk space can cause various issues, including 500 errors.

4. Check Logs:

   • Review the Plesk and web server error logs for any messages related to the "500 SB_Facade_Exception_NotFound" error. This might provide more specific information about the problem.

5. Check File Permissions:

   • Verify that the necessary files and directories related to Plesk have the correct permissions. Incorrect permissions can lead to various errors, including 500 errors.

6. Recreate Plesk Cache:

   • Clearing or recreating the Plesk cache might help if there is a cached file causing the issue. You can do this through the command line.

   • Example for Linux:

     Arduino

     plesk sbin packagemng --set-dirty-flag

7. Check for Corrupted Files:

   • It's possible that a file related to the Domains tab is corrupted. You might want to run a file integrity check to identify and replace any corrupted files.

8. Contact Plesk Support:

   • If the issue persists and you're unable to find a resolution, consider reaching out to Plesk support for further assistance. They can provide specific guidance and may be aware of any known issues related to the "500 SB_Facade_Exception_NotFound" error.

Remember to back up any critical data or configurations before making changes to your server or its settings, and proceed with caution when troubleshooting server-related issues.