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Defect Apps

A defective app is still installed and may continue to work, but Windows can no longer uninstall, repair, or update it. O&O AppBuster can detect these entries and remove them without requiring manual registry edits.

Defect apps are shown with the type Defect App.

What is broken​

Programs installed by the Windows Installer (MSI) do not carry their uninstaller inside the program folder. Windows keeps a cached copy of the installer package in its own storage and uses that copy whenever the app is to be uninstalled, repaired or updated.

If that cached .msi file disappears — because a disk cleanup tool deleted it, a drive error damaged it, or a migration left it behind — then:

  • Uninstalling fails. msiexec cannot find the package it needs.
  • Repair fails, for the same reason.
  • Updates fail, because an MSI update is applied against the cached package.
  • The entry stays in Programs and Features forever.

The program itself often continues to work. It is simply no longer manageable.

How O&O AppBuster detects it​

For every MSI-based app, O&O AppBuster:

  1. reads the uninstall command Windows recorded for it and confirms that it uses msiexec,
  2. extracts the product GUID from that command,
  3. looks up the cached package path (LocalPackage) in the Windows Installer user data — across all user profiles, not just yours,
  4. checks whether that file actually exists.

If the recorded package is missing, the app is marked as defect. If no package path is recorded at all but the product is still registered under HKCR\Installer\Products, that also counts as defect.

Apps whose uninstall command is a normal program rather than msiexec are never classified as defect — they carry their own uninstaller and are unaffected by this problem. Apps without a valid product GUID are skipped rather than guessed at.

Bridge apps are included

Programs that are installed by an MSI but also register as a Windows package — Visual Studio Code and TortoiseGit are typical — are checked too. For those, O&O AppBuster looks up the matching MSI registration by display name.

Removing a defect app​

This is the one case where O&O AppBuster deliberately does not use the app's own uninstaller — because that uninstaller cannot work. Instead it removes the app directly:

  1. The Windows Installer product registration is removed, including the installer's user-data entries.
  2. The uninstall registry entries are removed — from the 64-bit registry view, the 32-bit view and the current user's hive.
  3. The app's remaining files are deleted, if its install directory still exists.

No external installer process is started, so nothing can fail halfway through waiting for a package that is not there.

Select the app and click Uninstall, exactly as for any other app. After the next refresh (F5) it is gone from the list.

➡️ Removing apps

The app is still installed

This is the important difference from an orphaned app. An orphaned entry is a leftover — there is no working program behind it. A defect app is a working program with a broken installer. Removing it removes real software.

So decide first: do you want to keep using the program, or get rid of it?

  • Get rid of it → remove it here. This is the only way that works.
  • Keep it → leave it alone, or reinstall it over the top from the manufacturer's current setup file. A fresh installation writes a fresh cached package and makes the app manageable again.

When files are in use​

Because a defect app is usually still in use, it is more likely than average that some of its files are locked. O&O AppBuster offers the usual options: close the blocking programs and continue, schedule the deletion for the next restart, or skip the app.

Restart the PC when asked to — otherwise part of the program stays behind.

Preventing it​

Defective app entries are often caused when a cleanup tool removes files from the Windows Installer cache. Do not delete files manually from %WINDIR%\Installer; Windows needs this cache to repair, update, and uninstall software.

Do not let a cleaner delete %WINDIR%\Installer. Space saved there is paid for later.

When the Defect chip does not appear​

The Defect Smart View chip is only shown when defect apps were actually found. On a healthy system it is not there at all.