You may see an error message in the gUI that contains the following phrase:
“MongoDB.Driver.MongoConnectionException: Unable to connect to server localhost:27017”
Restarting the MongoDB service does not resolve this issue.
This issue is most likely caused by inconsistencies in one or both of the following files:
To ensure this is indeed the issue, review your Core log files for the driver-related information presence:
ERROR 2013-03-27T11:00:26  – WCFClientBase.EncapsulatedException ()
Caught an exception deserializing encapsulated exception of type ‘Replay.Core.Contracts.Storage.StorageConnectionException’
System.Runtime.Serialization.SerializationException: Unable to find assembly ‘MongoDB.Driver, Version=126.96.36.19900, Culture=neutral, PublicKeyToken=f686731cfb9cc103′.
You may also remove the inconsistent DLL files and repair the Core installation, provided you have not applied any custom binaries to your installation.