Problem installing on ubuntu 18.04 server

I’m trying to install duplicati on an ubuntu 18.04 server, following the instructions on Installation - Duplicati 2 User’s Manual but when I install it I get these errors:

dpkg: dependency problems prevent configuration of duplicati:
duplicati depends on libmono-2.0-1; however:
Package libmono-2.0-1 is not installed.
duplicati depends on libappindicator0.1-cil | libappindicator3-0.1-cil; however:
Package libappindicator0.1-cil is not installed.
Package libappindicator3-0.1-cil is not installed.
duplicati depends on gtk-sharp2; however:
Package gtk-sharp2 is not installed.

dpkg: error processing package duplicati (–install):
dependency problems - leaving unconfigured
Processing triggers for mime-support (3.60ubuntu1) …
Errors were encountered while processing:
duplicati

I did install mono as described, but I get the impression duplicati needs a different version. And it seems more packages are required. I’m not very experienced in linux yet, so does anybody know how to fix this?

Has nobody encountered this issue? If not, then I’m wondering what I’m doing wrong here…

Can you try manually installing each dependency it’s complaining about? For example:
sudo apt install libmono-2.0-1

Also, did you install Mono as explained here:
https://www.mono-project.com/download/stable/#download-lin-ubuntu

I have exactly the same problem. An attempt to install libmono-2.0-1 results in error:

The following packages have unmet dependencies:
 duplicati : Depends: libappindicator0.1-cil but it is not installable or
                      libappindicator3-0.1-cil but it is not installable
             Depends: gtk-sharp2 but it is not going to be installed

After installing mono-devel and running sudo dpkg -i duplicati_2.0.4.5-1_all.deb, run the next command

sudo apt install -f

It helped with my installation.

sudo apt dist-upgrade --fix-missing

This should help