https://github.com/duplicati/duplicati/tree/v2.0.3.4-2.0.3.4_canary_2018-04-02/Duplicati/Server/Database/Database%20schema is where the server database went to version 5, and I see that we’re now up to 6…
Although it’s not a great solution, sometimes these seemingly silent crashes leave a Duplicati-crashlog.txt although I’m not sure where they go. I’ll show the start of one that’s sitting in my Duplicati “updates” folder:
System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.Exception: A serious error occurred in Duplicati: System.Exception: Failed to create, open or upgrade the database.
Error message:
The database has version 5 but the largest supported version is 4.
This is likely caused by upgrading to a newer version and then downgrading.
If this is the case, there is likely a backup file of the previous database version in the folder C:\ProgramData\Duplicati.
This shows how to get from 5 to 4, however downgrades unfortunately have to be tailored to their upgrades.