Error or issue
Setting up the Remote MSCA Web Service that allows certificate issuance from a CA on a remote / untrusted domain.
Where this initially worked it stopped working after a while.
Cause
If the COM user (or Admin_ was logged onto the server console for the server hosting the Remote MSCA Web Service, then certificate issuance worked fine. As soon as the console was logged off the certificate issuances stopped.
Resolution
The resolution was to set the advanced Application Pool setting “load user profile” to “True” in IIS on the Remote MSCA Web Service server.
In Internet Information Services (IIS) Manager, set the following option for the MyIDMSCAEnrollment_Pool application pool: Advanced Settings > Process Model > Load User Profile – set to True.