When I awoke this morning I was greeted with a high priority email indicating that our CRM server down.  I promptly discovered that we were receiving a very descriptive "Invalid Action: The selected action was not valid" error message.

I quickly Googled the error message and found a single entry where the issue was disk space.  Well, it turns out that disk space wasn't the issue, but it prompted me to clean up the transaction logs.  That was a nice detour, but it didn't get me closer to solving the problem.

The next thing I checked was the system's Application Event Log.  Lo and behold, I found the following error message:

Source:   MSCRMKeyGenerator
Event ID: 18949

Current active key (KeyType : CrmWRPCTokenKey) is expired. This can indicate that a key is not being regenerated properly. Current Active Key : CrmKey(Id:c2e0c738-dc7a-dd11-b61e-00188b3466e9, ScaleGroupId:00000000-0000-0000-0000-000000000000, KeyType:CrmWRPCTokenKey, Expired:True, ValidOn:09/04/2008 23:50:21, ExpiresOn:10/07/2008 23:50:21, CreatedOn:09/04/2008 23:50:21, CreatedBy:NT AUTHORITY\NETWORK SERVICE. Key Setting :

Fortunately, this problem was easily solved by running services.msc and starting the Microsoft CRM Asynchronous Processing Service.