Files Not Removed on Uninstall Due to Component GUID Issues in WiX MSI

[Bondarenko1990]

Question

When building and deploying multiple MSI packages, I have encountered issues where some files are not removed during uninstall, or uninstall is blocked with messages like:
Disallowing uninstallation of component: {45E7FE64-9B81-46D1-B1F1-35D7EDB1E628} since another client exists

Root Cause:
This is caused by duplicate or reused component GUIDs across different MSI packages or versions. Windows Installer reference-counts components by GUID, so if the same GUID is used in multiple installers, the component is treated as shared and will not be removed until all "clients" are uninstalled.
Steps to Reproduce:

1. Build and install MSI package with a component GUID (e.g., {45E7FE64-9B81-46D1-B1F1-35D7EDB1E628}).
2. Attempt to uninstall one of the packages.
3. Observe that the file is not removed, or uninstall is blocked with a "since another client exists" message.

Additional Description for the Issue:
I tried to find the problematic component GUIDs in the Windows registry (under HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UserData\S-1-5-18\Components), but did not find any entries for them.
I also tried uninstalling the application using Revo Uninstaller, but the problem persists. Interestingly, if I change the component GUID in my WiX file and rebuild the MSI, the files are deleted correctly on uninstall. However, I want to keep the existing GUIDs and have the files uninstall properly.
What should I do so that the files are deleted with the existing GUIDs?
I suspect this issue may have been caused by an incorrect or incomplete uninstall in the past, which left the Windows Installer database in an inconsistent state.

Fragment:

Actual Result:
Files remain after uninstall, or uninstall is blocked due to shared component GUIDs.

Expected Result:
Uninstall should remove all files and components associated with the product.

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