This only started a few months ago but took me a bit to narrow down the problem. The backup seems to complete but the app crashes when sending the success email. If I disable email notifications the backup will show as completed in the app.
I saw another post that I thought might be related after posting so I checked System Info. It’s showing * MonoVersion : 184.108.40.206.
I’m not completely sure that it’s just the connection to the server that is lost. I also lose the app icon for the daemon and have to re-launch the duplicati app.
Edit: This is the macOS version.
Resolutions are not always stated, but in the below someone fixed a problem like that by upgrading mono:
I’m not exactly sure where your mono stack trace shows up, but at least one report found it in their syslog.
Looks like that fixed it. Updated to latest stable mono (220.127.116.11) no more crashes. Thanks for the help.