Hi @Bunny welcome to the forum!
That problem is caused by Mono not being maintained, and Duplicati depending on Mono.
You can dig into some of the other posts on the topic.
Or you can try the canary builds which no longer uses Mono:
How so? Dependencies are around, but in other versions.
Install fails on Ubuntu 24.04 LTS - unmet dependencies #5178 has my two posts on alternatives, however I’m not familiar enough with linking and builds to say if a “universal” package is possible.
Since it is not maintained, the packages will (most likely) be dropped from distros going forward.
Deprecation message on https://www.mono-project.com
The Mono Project (mono/mono) (‘original mono’) has been an important part of the .NET ecosystem since it was launched in 2001. Microsoft became the steward of the Mono Project when it acquired Xamarin in 2016.
The last major release of the Mono Project was in July 2019, with minor patch releases since that time. The last patch release was February 2024.
We are happy to announce that the WineHQ organization will be taking over as the stewards of the Mono Project upstream at wine-mono / Mono · GitLab (winehq.org). Source code in existing mono/mono and other repos will remain available, although repos may be archived. Binaries will remain available for up to four years.
Microsoft maintains a modern fork of Mono runtime in the dotnet/runtime repo and has been progressively moving workloads to that fork. That work is now complete, and we recommend that active Mono users and maintainers of Mono-based app frameworks migrate to .NET which includes work from this fork.
We want to recognize that the Mono Project was the first .NET implementation on Android, iOS, Linux, and other operating systems. The Mono Project was a trailblazer for the .NET platform across many operating systems. It helped make cross-platform .NET a reality and enabled .NET in many new places and we appreciate the work of those who came before us.
Thank you to all the Mono developers!
Agree for future, but maybe not for Ubuntu 24.04. At one time I guessed version bump was GTK2 removal. I did find and install https://packages.ubuntu.com/noble/gtk-sharp3, but launch still failed:
$ mono ./Duplicati.GUI.TrayIcon.exe
Unexpected error: System.TypeLoadException: Could not load type of field 'Duplicati.GUI.TrayIcon.GtkRunner:m_trayIcon' (1) due to: Could not load file or assembly 'gtk-sharp, Version=2.12.0.0, Culture=neutral, PublicKeyToken=35e10195dab3c99f' or one of its dependencies.
at Duplicati.GUI.TrayIcon.Program.RunTrayIcon (System.String toolkit) [0x00027] in <3ea059db9f9241b999c39793a8f6f091>:0
at Duplicati.GUI.TrayIcon.Program.StartTray (System.String[] _args, System.Collections.Generic.Dictionary`2[TKey,TValue] options, System.String toolkit, Duplicati.GUI.TrayIcon.HostedInstanceKeeper hosted, System.String password, System.Boolean saltedpassword) [0x00066] in <3ea059db9f9241b999c39793a8f6f091>:0
I found the .csproj file, and found the BuildSupport folder, and guessed version gets built in.
Short of running Canary (which works well now except for some UI, but has other work coming), short of seeing if versioning can be tweaked for a 2.0.8.1 hotfix (for everyone or just this issue?):
Duplicati not been installed in Linux Mint 22 has a not-great workaround for these new OS:
True, it could work for 24.02. I did not find the updated gtk-sharp package back when I first encountered the issue, so I (wrongly) assumed gtk-sharp was just not updated.
Yes, there is likely a version bump in gtk-sharp3 libraries so we would need to re-build from source with new bindings. That version would then not work with gtk-sharp2, unless we do some assembly-redirect magic.