Unable to locate Sophos Autoupdate MSI

As you have on-prem, to get the same version of the msi needed you might need to obtain it from a computer that is running the same version, maybe it's been off for a while and just hasn't updated or you might need to create a new subscription in SUM to create a new CID of an older package to obtain the MSI file.

As Christian points out, the first step is to find the expected file name for the cached MSI and the version of the component installed.  You can find both of these under:

\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UserData\S-1-5-18\Products\[CODE]\InstallProperties

DisplayVersion
LocalPackage

As you now have the version installed you need to find the MSI that matches that version.  The SEC UI allows you to see the version of components in a subscription so that will help.  Once you find the Sophos AutoUpdate.msi file for the version installed you can copy it to the same location as defined in the LocalPackage.  The uninstall should then work,

Worse case is you can use SophosZap and it will blow it all away.

I agree with SophosZap, it might be easier and faster to just wipe Sophos from the machine and reinstall it here.

I agree with SophosZap, it might be easier and faster to just wipe Sophos from the machine and reinstall it here.