"We're also not currently bundling the dependencies for MonoDevelop (and doing so is a bit complicated), so the easiest way to ensure you can run the bundled MonoDevelop is to first install the upstream MonoDevelop from the Ubuntu Software Center." http://forum.unity3d.com/threads/unity-on-linux-release-notes-and-known-issues.350256/
The same issue here and fixed by installing MonoDevelop from the repos. I recommand you to use Mono's repository for your distribution (apt, yum, yast) because the MonoDevelop and the Mono runtime are updated to the latest version (http://www.mono-project.com/download/#download-lin).
i'd focus on getting monodev to work, odds are you missed something, you should as in your distro's forum about installing mono dev, not here, they can't help you. I'm not on linux atm, so i can't further assist you, but i'd try removing and deleting everything, then re-installing from the official repos.
@blue-amarok I recommand you to use the Mono's repository to install the latest Mono runtime and MonoDevelop, you can add the repo by following this link http://www.mono-project.com/docs/getting-started/install/linux/#debian-ubuntu-and-derivatives . It worked fine for me (Kubuntu 15.10). Note that this repo is for debian like distributions.
Just wanted to reply and said that the post from @demonixis is what fixed MonoDevelop for me. The editor still throws errors when I close tabs, but the project loads properly now. Edit: This is on Linux Mint KDE 17
There are still people with this issue. I have installed the most recent version of MonoDevelop, but I'm not sure how to get it to open up the script files. I pointed my external script editor to /usr/bin/monodevelop. That does open the program, but not the script file itself. What am I missing? EDIT: I have found the solution to this issue. http://forum.unity3d.com/threads/li...odevelop-refuse-to-start.378047/#post-2455128 See my comments there.
Same here, demonixis' link works perfectly for me on Ubuntu 15.04 with monodevelop installed from Software Center.
Maybe this can help too -> http://forum.unity3d.com/threads/monodevelop-did-not-work.353764/#post-2602623