This issue is caused by a mismatch of DLL files between your SelectHR and SelectPay system.
This issue can occur following an update to SelectPay (new service pack being applied).
If you are seeing this error in the audit log of the SelectHR Admin Tool, please raise a new case online and reference the title of this article.
Error: The deserializer has no knowledge of which type to deserialize. Check that the type being serialized has the same contract as the type being deserialized
Error: The deserializer has no knowledge of which type to deserialize.
Written by Harry Ledger