PureMessage for Microsoft Exchange: error 1603 'Error applying transforms'

Issue

When you try to upgrade or remove PureMessage for Microsoft Exchange, you receive the error

Error 1603 - 'Error applying transforms. Verify that the specified transform paths are valid'.

This error message refers to a file called 1033.MST.

Sophos product and version

PureMessage for Microsoft Exchange

What to do

Open Regedit
Browse to HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Installer\
Products\19962AEDA63B38A4088FEB3F88B80202.
Right-click the value 'Transforms' and select 'Modify'. This displays a value similar to 'C:\DOCUME~1\user account\LOCAL~1\Temp\_is87\1033.MST'.
Delete the contents of the Value data field.
Run the upgrade or uninstall again.

Technical information

The temp folder has been cleared out sometime in the past, and this has since removed the 1033.MST file.

If you need more information or guidance, then please contact technical support.