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MSI error code 1638: “Another version of this product is already installed”

When you try to remove an application, you receive the following error: “Another version of this product is already installed” with the error code 1638.


This is a problem with minor/major versions of the installed product. When a GUID of a msi package changes (when an msi is generated for example), the product will detect itself as another version.

Solution 1

Try to get the original msi. You can check GUID’s of the installed software and the msi match. You can find the GUID in the uninstall information:

x86 applications: HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall
x64 applications: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall

Try to find the specific uninstall information by, for example, searching for the name of the software in the subkey. Mostly the GUID is shown in the key ‘ModifyPath’ or ‘UninstallString’. If the GUID’s match, it is possible you can uninstall the application with the msi.

Solution 2

If there is no way to get the original msi or the error persists, you can delete the installation information. This information resides in:


The software installation info is present under the SID of the user who installed the software. The SID ‘S-1-5-18′ belongs to the system account. So, if the software is installed by deployment software, such as System Center Configuration Manager, the information will be present under this subkey.

The easiest way is to find the specific software by searching from the subkey ‘UserData’.


Next, rename the whole key (which is the GUID of the software), under which you found the software information. Rename it like: 000021599B0090400100000000F01FEC.bak so you have the possibility to restore it.

Now try to uninstall the software again with the msi installer you have.

1 Comment

  1. November 21, 2014    

    Awesome solution. Did you know you can also find the GUID and lots of other metadata from MyUninstaller? Very small, but handy tool for uninstalling software.

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