Looks like some people are having issues with newly installed FMS, where FMS refuses to open files.
Someone out there mentioned the following:
Beware when installing a new FM Server, the default fmcert that it comes with suffers from the same expiring validity of other older fmcert files. If you are troubleshooting why files fail to open, try importing a valid license file first. To verify, the default cert file is here
CStore/LicenseFile/DefaultCert.fmcertso you can see for yourself.
The author is not a member of this community, and other elements will lead me to favor not mentioning the author. I am not attempting to get credits for this, simply am not aware that the author would seek attribution in this case.
I did not come across this problem myself, but have a few contacts who said this fixed the issue and let FMS open the files.