How to fix Error 1320 on Windows 11

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Troubleshooting Guide: Windows Installer Error 1320

Why This Error Happens

Error 1320 typically occurs during software installation, repair, or removal when the Windows Installer service attempts to modify user group memberships and encounters a conflict. This is often caused by corrupted user profile paths, an excessively long file path exceeding the TEMP folder’s character limit, or insufficient permissions on the local user account attempting to write to the Windows Installer cache. In many cases, the root issue lies in a misconfigured or redirected TEMP/TMP environment variable pointing to an inaccessible or overly nested directory.

Step-by-Step Resolution Guide

Step 1: Verify and Reset the TEMP/TMP Environment Variables

  • Press Win + R, type sysdm.cpl, and press Enter.
  • Navigate to the Advanced tab and click Environment Variables.
  • Under “User variables,” check that TEMP and TMP point to %USERPROFILE%\AppData\Local\Temp (avoid long nested paths).
  • Update the same values under “System variables” to C:\Windows\Temp if they appear altered.
  • Restart your computer for the changes to take effect.

Step 2: Check User Account Permissions

  • Open Computer Management by right-clicking the Start button and selecting it from the list.
  • Navigate to Local Users and Groups > Users.
  • Right-click your current user account, select Properties, and go to the Member Of tab.
  • Ensure the account is not duplicated in the Administrators group or the specific group referenced in the installer error.
  • If a duplicate entry exists, select it and click Remove, then click Apply.

Step 3: Clear the Windows Installer Cache

  • Open the Run dialog (Win + R) and type %windir%\Installer.
  • Do not delete files directly; instead, back up the folder by copying it to a temporary location (e.g., D:\InstallerBackup) in case a file is needed by another installed application.
  • Restart the Windows Installer service by opening services.msc, right-clicking Windows Installer, and selecting Restart.

Step 4: Run the Installation with Elevated Privileges

  • Right-click the installer executable (.exe or .msi) and select Run as administrator.
  • If the error persists, try running the installer from a Local Administrator account rather than a Microsoft/Azure AD linked account, as domain-based permission syncing can sometimes trigger this specific group-membership conflict.

Alternative or Verification Steps

  • Verification: After completing the steps above, attempt the installation again and monitor the Windows Event Viewer (eventvwr.msc) under Windows Logs > Application to confirm the Event ID 1320 no longer appears during the setup process.
  • Alternative Fix: If the issue persists, run the built-in Program Install and Uninstall Troubleshooter from Microsoft’s support site, which automatically resets corrupted registry keys associated with the Windows Installer service.