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Moving from Excel 2013 to Excel 2010 leaves problematic .dll's behind

This is a known issue which affects EASA on a Windows system where an earlier version of Excel (2010) is installed after uninstalling a later one (2013).

Excel 2013 leaves behind two .dll files which are not compatible with a later installation of Excel 2010 unless the files are manually removed before Excel 2010 is installed.

  • the files are,
    • FM20.dll
    • FM20ENU.dll

In this case the error message is, “Class not registered.Looking for object with CLSID {AC9F2F90-E877-11CE-9F68-00AA00574A4F}”


A more detailed description of the problem follows.

Office 2013 installs VBA 7.1 and updated versions of FM20.dll which has a dependency on the VC10 redistributables (specifically msvcr100.dll).

When VBA 7.1 is uninstalled it does not remove FM20.dll but whatever application is using VBA most likely will remove the VC10 redistributables. This step is required as installing an application that uses an earlier version of VBA (eg. VBA 6.x ) won't overwrite the newer version of FM20.dll.

Delete FM20.dll and install Excel 2010 or install the VC10 redistributable.