Download

1 Add the Mono repository to your system

The package repository hosts the packages you need, add it with the following commands.

Note: the packages should work on newer Ubuntu versions too but we only test the ones listed below.

Ubuntu 20.04 (amd64, armhf, arm64, ppc64el)

sudo apt install ca-certificates gnupg
sudo gpg --homedir /tmp --no-default-keyring --keyring /usr/share/keyrings/mono-official-archive-keyring.gpg --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF
echo "deb [signed-by=/usr/share/keyrings/mono-official-archive-keyring.gpg] https://download.mono-project.com/repo/ubuntu preview-focal main" | sudo tee /etc/apt/sources.list.d/mono-official-preview.list
sudo apt update

Ubuntu 18.04 (i386, amd64, armhf, arm64, ppc64el)

sudo apt install ca-certificates gnupg
sudo gpg --homedir /tmp --no-default-keyring --keyring /usr/share/keyrings/mono-official-archive-keyring.gpg --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF
echo "deb [signed-by=/usr/share/keyrings/mono-official-archive-keyring.gpg] https://download.mono-project.com/repo/ubuntu preview-bionic main" | sudo tee /etc/apt/sources.list.d/mono-official-preview.list
sudo apt update

Ubuntu 16.04 (i386, amd64, armhf, arm64, ppc64el)

sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF
sudo apt install apt-transport-https ca-certificates
echo "deb https://download.mono-project.com/repo/ubuntu preview-xenial main" | sudo tee /etc/apt/sources.list.d/mono-official-preview.list
sudo apt update

---

2 Install Mono

sudo apt install mono-devel

The package mono-devel should be installed to compile code.

The package mono-llvm-support should be installed for LLVM JIT/AOT support. See here for more about LLVM Mono.

The package mono-complete should be installed to install everything - this should cover most cases of "assembly not found" errors.

The package mono-dbg should be installed to get debugging symbols for framework libraries - allowing you to get line numbers in stack traces.

The package referenceassemblies-pcl should be installed for PCL compilation support - this will resolve most cases of "Framework not installed: .NETPortable" errors during software compilation.

The package ca-certificates-mono should be installed to get SSL certificates for HTTPS connections. Install this package if you run into trouble making HTTPS connections.

The package mono-xsp4 should be installed for running ASP.NET applications.

---

3 Verify Installation

After the installation completed successfully, it's a good idea to run through the basic hello world examples on this page to verify Mono is working correctly.

Notes

Mono on Linux before 3.12 by default didn't trust any SSL certificates so you got errors when accessing HTTPS resources. This is not required anymore as 3.12 and later include a new tool that runs on package installation and syncs Mono's certificate store with the system certificate store (on older versions you had to import Mozilla's list of trusted certificates by running mozroots --import --sync). Some systems are configured in a way so that the necessary package isn't pulled in when Mono is installed, in those cases make sure the ca-certificates-mono package is installed.

sudo apt install dirmngr ca-certificates gnupg
sudo gpg --homedir /tmp --no-default-keyring --keyring /usr/share/keyrings/mono-official-archive-keyring.gpg --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF
echo "deb [signed-by=/usr/share/keyrings/mono-official-archive-keyring.gpg] https://download.mono-project.com/repo/debian preview-buster main" | sudo tee /etc/apt/sources.list.d/mono-official-preview.list
sudo apt update

sudo apt install mono-devel

sudo apt install dirmngr ca-certificates gnupg
sudo gpg --homedir /tmp --no-default-keyring --keyring /usr/share/keyrings/mono-official-archive-keyring.gpg --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF
echo "deb [signed-by=/usr/share/keyrings/mono-official-archive-keyring.gpg] https://download.mono-project.com/repo/debian preview-raspbianbuster main" | sudo tee /etc/apt/sources.list.d/mono-official-preview.list
sudo apt update

sudo apt install mono-devel