Resolving "Unable to Lookup SID for Name" Errors in Plesk for Windows

Plesk operations on Windows can fail with "Unable to lookup SID for name" errors, affecting backups, migrations, and file management. This guide offers simple steps to fix these issues and keep your site running smoothly.

Symptoms

You might see:

• "Unable to lookup SID for name IUSR_example.com: (1332) No mapping between account names and security IDs was done. (Error code 1)"
• Backup errors: "Unable to back up files from C:\Inetpub\vhosts\example.com owned by system user. Failed to create archive."
• Migration warnings: "Can not deploy web-content of domain example.com. The user name could not be found."
• Permission failures in File Manager: "The user name could not be found. (Error code 2221)"

Cause

The error happens when Plesk can’t find a user account (e.g., IUSR_example.com) on your system.

Resolution

1. Access the Server: Log in via Remote Desktop (RDP) with admin rights.
2. Open Command Prompt: Search for "cmd," right-click, and select Run as Administrator.
3. Fix the User: Run net user IUSR_example.com /add to recreate the missing user (adjust as needed). Check with your host for specifics.
4. Apply to Domains: Repeat for other domains (e.g., example.com) or ask your provider for help.
5. Retest: Try the failed task again in Plesk (e.g., backup or permission change).