Fm20.dll errors are caused by situations that lead to the deletion or corruption of the Microsoft Forms DLL file. In some cases, these errors can indicate a registry problem, a virus or malware issue, or even a hardware failure.

Recover the file from the Recycle Bin. The simplest possible cause of a "missing" fm20.dll file is that you accidentally deleted it.

If you suspect this, but you've already emptied the Recycle Bin, you may be able to recover the file with a free file recovery program.

Reinstall the program that uses the file. If fm20.dll errors occur when using a particular program, reinstalling the program should replace the file.