A Full or a Delta Synchronization stops running rather quickly. You notice that the status on the Operations Tab (Run History) is "stopped-extension-dll-load". Investigating the issue, you notice the following error in the Application Event Log.
Application Event Log
Event ID: 6152
Event Source: FIMSynchronizationService
The management agent 'MyADMA' failed on run profile 'DI-DS'. The run step stopped because a required rules extension 'MyADMAExtension.dll' could not be loaded. User Action Verify that the rules extension is located in the Extensions directory. If the extension is present, confirm that the version of the .NET framework that can run the extension is installed on the server and that a supportedRuntimes entry in the configuration files specifies that version. The synchronization engine will not be able to load an extension that is built with a newer version of the .NET framework than the version of the .NET runtime it is hosting.
We were not able to fully diagnose the cause of this specific issue, but here are some troubleshooting steps that will help guide you in the correct direction.
In this particular issue, we rebuilt the Management Agent Extension and things started working fine.