Follow these instructions exactly as indicated.
Install a fresh copy of Linux Mint 19.2 "Tina", and reboot your computer.
Once your computer system has rebooted, log in as your normally would and you should now see the update manager indicating that you have updates available.
Click it and open the update manager. The first time you do this, it will indicate that it needs to update itself. Apply the update.
Once the update manager updated itself, you will see several additional updates that need installed. Install those as well.
There is probably a kernel update in the updates that you just installed, so go ahead and reboot your system again.
Once the system has rebooted, log in as you normally would.
Open a terminal window, and issue the following commands.
Your system should now have the current version of Mono installed, next we need to install the monodevelop packages from the official repository.sudo su
(enter your password when prompted.)
apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF
echo "deb https://download.mono-project.com/repo/ubuntu stable-bionic main" | tee /etc/apt/sources.list.d/mono-official-stable.list
(The system may report back that there are updates available, do not install the updates until we're finished.)
apt install mono-complete --install-recommends -y
In the terminal window you have open, issue the following commands.
Once your computer has rebooted, log into your system as you normally would.apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF
echo "deb https://download.mono-project.com/repo/ubuntu vs-bionic main" | tee /etc/apt/sources.list.d/mono-official-vs.list
(The system may report back there are updates available. Do not install them yet.)
apt install monodevelop --install-recommends -y
If the system update manager indicates that you have updates available, go ahead and allow the system to update as needed.
Click on your mint menu icon and look for the section named "Development", and click on MonoDevelop.
Congratulations, you should now have the lastest stable versions of Mono and Monodevelop installed.