I use a VPN (Mullvad) where I via split tunneling have excluded all Duplicati processes to ensure it connects directly. This worked beautifully on previous versions. After updating to 2.1.0.4_stable_2025-01-31, all connections fail with a “An attempt was made to access a socket in a way forbidden by its access permissions.”. This includes backup connections (I use WebDAV) and connections to updates.duplicati.com:443.
If I disable the VPN entirely, it works beautifully again.
It looks somewhat similar to this topic, but with a different error.
I wonder if the process utilized for outside connections changed between the two versions? Perhaps something new that needs to be added to the VPN exclusion list. I have added all that matches Duplicati*.exe.
If you were previously using Duplicati 2.0.8.1, then the .NET runtime was updated from .NET4 to .NET8 (aka .NET Core). Much of the .NET core code was rewritten from the previous instance, so it is highly likely that “something” changed.
Unfortunately, I don’t see any great explanations or similar descriptions. Since you get the error from both the update server and the destination, I am thinking this is some permission setting that is active when VPN is active.
I don’t have a good guess as to why it only affects Duplicati.
There is an SO thread that suggests restarting the “Host Network Service”:
Do you have the problem as well, if you restart Duplicati after connecting to VPN?
Thank you so much for the feedback. I really appreciate it.
I tried various combinations of starting Duplicati after connecting the VPN, before connecting the VPN along with restarting various Windows network services, but the issue persisted.
What did work (and this makes very little sense to me) was REMOVING all Duplicati processes from the VPN split tunnelling. That is, now that I’m forcing all connections through the VPN everything works again.
Just to sum up:
Previous version of Duplicati, VPN set to exclude all Duplicati processes = works.
Current version of Duplicati, VPN set to exclude all Duplicati processes = connection denied.
Current version of Duplicati, VPN set to include all Duplicati processes = works.
While I don’t understand how, I have no doubt the problem has to do with Mullvad or Windows and not Duplicati.
