I had an interesting one recently when submitting a certificate request to a Windows Certificate Authority using certreq.exe. The error that came back was:
The disposition message is “Error Parsing Request The request subject name is invalid or too long. 0x80094001 (-2146877439)”
I found several links to possible solutions but, as it turns out, the problem in my case was the subject name (specified an X.500 DistinguishedName) was too long. It seems that the CA limits the subject name field to 64 characters. Mine was around 80 characters, which is not unusual for a DN.
The workaround is to remove the 64 character limit by running the following command:
certutil -setreg ca\EnforceX500NameLengths 0
The CA service needs to be restarted after running the command.
The Microsoft TechNet article that provides more detail can be found here.