Packages have unmet dependencies on 18.04 upon mongodb install

Solution 1:

From the logs, looks like you have mongodb installed from Ubuntu 18.04 and then you modify the repo to add the one from mongodb. Try removing the mongodb from Ubuntu repo first before installing the one from mongodb repo.

Ubuntu came with mongodb version 3.6.3 and it is already installed. Remove it first.

sudo apt-get purge mongodb mongodb-server mongodb-server-core mongodb-clients
sudo apt-get purge mongodb-org
sudo apt-get autoremove

Then try installing again

sudo apt-get update
sudo apt-get install mongodb-org

Edited, problem purging...

Try forcefully removing the two offending packages individually.

sudo dpkg --remove --force-remove-reinstreq mongo-tools
sudo dpkg --remove --force-remove-reinstreq mongodb-server-core

After that you can this again,

sudo apt-get --fix-broken install

Solution 2:

I used apt remove mongodb-org, which successfully cleaned the broken dependencies and it immediately returned to normal

Thanks all