This Knowledgebase article provides information about the Error Message: U16 Serious configuration mismatch.
The system displays the Error Message: U16 Serious configuration mismatch.
The presence of two active servers, instead of active-passive.
Run the Server Configuration wizard from taskbar icon. Note: The NFServerR2 service must be stopped to enable the Server Configuration wizard.
Make sure that one server is set to active and the other passive. Check that if the application is running that it is only running on the side that is configured as active. Start Neverfail and allow to synchronize.
This error can also appear in certain circumstances where the drive letters are not identical on both servers.