Error 1638
Another version of this product is already installed. Installation of this version cannot continue.
A different version is already on the machine and this package will not install over it. Uninstall the existing version first.
What it actually means
MSI packages declare an upgrade code that determines what they can replace. When the installed version is not covered, the installer refuses rather than risking a broken mix of two versions.
How to fix it, in order
Ordered by how often each one is the answer, not by how clever it sounds.
- 01Uninstall the existing version from Settings, Apps, then run the installer again.
- 02If it does not appear in the list, it was installed for a different user account or its entry is damaged. The product code lets you remove it directly with "msiexec /x {GUID}".
- 03Look up the product code on our page for that program: we publish the exact GUID for the version we index.
- 04If the installed version is newer than the one you are installing, that is the whole explanation. Downgrading needs the old version removed first.
We publish the product codes
The usual advice at this point is to hunt for the GUID with Get-WmiObject or in the registry. For the programs we index, the code is printed on the software page along with the exact msiexec command.
Common questions
- How do I fix error 1638?
- Uninstall the version already installed and run the installer again. If it does not show in Settings, Apps, remove it with "msiexec /x {product code}" using the GUID for that version.
Before you retry the installer
If the package came from anywhere other than the publisher, confirm it is the file they actually shipped. Check its SHA-256 against our index, which settles in seconds whether you are debugging an installer or a damaged download.