Compiling Mono on Windows

To build Mono on Windows, a Cygwin setup is required since it provides some tools required by Mono at build time. You’ll also need Visual Studio 2017 or later installed.

Instructions are available for building without the use of Cygwin.

Install prerequisites

  • Enable Developer Mode in the Windows 10 Settings app (Update & Security -> For developers tab)
  • Download and install 64 bit Cygwin from
  • Install Visual Studio 2017 or later - Community Edition works fine.
  • Download and install Mono for Windows or use monolite build step as described below.
  • Run the following command in cmd.exe to install the required packages:
setup-x86_64.exe -P autoconf,automake,bison,gcc-core,gcc-g++,mingw64-i686-runtime,mingw64-i686-binutils,mingw64-i686-gcc-core,mingw64-i686-gcc-g++,mingw64-i686-pthreads,mingw64-i686-w32api,mingw64-x86_64-runtime,mingw64-x86_64-binutils,mingw64-x86_64-gcc-core,mingw64-x86_64-gcc-g++,mingw64-x86_64-pthreads,mingw64-x86_64-w32api,libtool,make,python,gettext-devel,gettext,intltool,libiconv,pkg-config,git,curl,wget,libxslt,bc,patch,cmake

Make sure that the following GIT setting is set to avoid issues with line endings:

git config --global core.autocrlf input

Building Mono from a Release Package

Mono releases are distributed as .tar.bz2 packages from the Mono web site. Once you have your dependencies installed all you need to do is run the following command where VERSION is the package version number and PREFIX is your installation prefix:

tar xvf mono-$VERSION.tar.bz2
cd mono-$VERSION

And then you can continue with the appropriate commands below, without running git clone and cd mono.

Build Mono 64-bit using Visual Studio

The native runtime libraries can be built using Visual Studio and msbuild. However the .NET libraries and tests must currently be built in cygwin using make. The steps below describe how you use cygwin to first configure the build, then build the runtime libraries in Visual Studio and use the Visual Studio built mono executable when building the class libraries and tests in cygwin.

Below we specify 64-bit build and sgen GC (The boehm GC is not supported on 64-bit windows), installing build into $PREFIX where mono distribution already exists (replacing). NOTE, in order to keep existing mono distribution untouched, setup a different $PREFIX. You may also only set PATH to point to existing mono distribution and not specify $PREFIX at all.

git clone
cd mono
./ --prefix=$PREFIX --host=x86_64-w64-mingw32 --disable-boehm

32-bit build

To build Mono 32-bit, run autogen with --host=i686-w64-mingw32 instead and choose 32-bit when building in Visual Studio.

Now open the mono solution msvc\mono.sln in Visual Studio. Rebuild the solution and point the MONO_EXECUTABLE to the mono exe you just built in Visual Studio. Eg:

export MONO_EXECUTABLE=/cygdrive/c/monolocation/mono-4.2.1/msvc/build/sgen/x64/bin/Release/mono-sgen.exe

if you built 64-bit Release version.

Command line using msbuild.exe

Instead of building from within Visual Studio you can use msbuild.exe directly in the cygwin terminal:

/cygdrive/c/Program\ Files\ \(x86\)/MSBuild/14.0/Bin/MSBuild.exe /p:PlatformToolset=v140 /p:Platform=x64 /p:Configuration=Release /p:MONO_TARGET_GC=sgen msvc/mono.sln

Use desired parameters in the Platform and Configuration parameters to change between 64 and 32 bit builds as well as Release and Debug builds.

If only changes has been done to the native code and no changes have been done to base class libraries or .NET tests, building/rebuilding using Visual Studio solution is enough. If, however there are changes done to the base class libraries or tests, you need to run make in cygwin to rebuild the class libraries and/or tests.

Building without installed Mono distribution

If no Mono distribution is installed, you can build using monolite. Just run the below before running make:

make get-monolite-latest

Next step is to build the BCL and all System libraries. Go back to cygwin and run make:

make install

It is possible to parallelize the cygwin build passing in for example -j8, where 8 in this case is the number of parallel builders to run.

If you run make V=1 and see this after a successful BCL build:

make[8]: Entering directory '/home/user/work/mono/mcs/class/corlib'
CYGWIN=winsymlinks:nativestrict ln -s /home/user/work/mono/mcs/class/lib/build-win32 /home/user/work/mono/mcs/class/lib/build
ln: failed to create symbolic link '/home/user/work/mono/mcs/class/lib/build': Operation not permitted
make[8]: *** [../../build/library.make:336: ../../class/lib/build/.stamp] Error 1

you need to enable Developer Mode in the Windows 10 Settings app (Update & Security -> For developers tab) which will allow your user to create symbolic links without administrator privileges.

If you use an earlier Windows versions you need to run the build as administrator.

Building with Windows Subsystem for Linux (WSL)

Normally you should be able to just use the Linux instructions. Currently your autogen/configure invocations must include --with-csc=mcs, as building with Roslyn triggers as severe (system-crashing) known issue.