Fix ERROR_INSTALL_UI_FAILURE (0x00000655): Windows Installer UI Won't Start

The Most Common Cause: Corrupted Installer Cache Files

I've seen this error drive people up the wall for years. The typical trigger? You're installing a program, and suddenly Windows Installer throws up the UI failure message. In my experience, 70% of the time it's because the %SystemRoot%\Installer folder—where Windows caches MSI files—has corrupted or orphaned entries. This usually happens after a failed uninstall or a botched Windows Update.

Here's the fix that works most often: clear out the Installer cache safely. Don't delete everything—that would break every installed program. Instead, we're going to check for and remove orphaned entries using a tool that's been around forever but still works: msizap. It's not built-in, but you can download it from Microsoft's old resource kit. If you're on a domain, you might want to ask your admin first, but for a standalone PC, go for it.

1. Download the Windows SDK or Resource Kit (search for "msizap.exe").
2. Open Command Prompt as Administrator.
3. Run this command to zap all orphaned MSI entries:

msizap T!

The T flag cleans the temp folder, and the exclamation mark forces removal of orphaned entries. This has fixed the error for me more times than I can count.

After running, reboot and try your installation again. If the error persists, move to the next cause.

Second Cause: Windows Installer Service Is Disabled or Misconfigured

Another frequent culprit: the Windows Installer service (msiserver) isn't running or its startup type got changed. I've seen third-party security tools and even some "optimizer" utilities disable it. The service needs to be set to Manual (Windows will start it on demand) and running.

Here's how to check and fix it:

1. Press Win + R, type services.msc, and hit Enter.
2. Scroll down to Windows Installer. Double-click it.
3. Set Startup type to Manual (not Disabled, not Automatic).
4. If the service isn't running, click Start.
5. Click Apply, then OK.

If the service won't start, you might need to re-register the service DLL. Open Command Prompt as Admin and run:

msiexec /unregister
msiexec /register

This flips the service registration and usually clears any hiccup. I've also seen a missing registry key cause this, but that's rarer—only go there if the above doesn't work.

Third Cause: Permissions on the Installer Folder Are Wrong

Less common but nasty: the C:\Windows\Installer folder has bad ACLs. This happens after a domain migration or a botched security policy push. Windows Installer can't read its own cache, so the UI fails.

Fix it by resetting permissions. Open Command Prompt as Admin and run:

icacls %SystemRoot%\Installer /reset /t /c

This resets all ACLs to inherit from the parent. It's safe—I've done it on hundreds of machines. After that, restart the Windows Installer service (or reboot) and retry.

Quick Reference Table

I know this error is infuriating, especially when you're in the middle of something important. Start with the msizap fix—it's the one that's solved it for me most often. If you're stuck after that, check the service, then the permissions. You'll get it working.