This document describes how to build an Aeternity node from source on Windows using MSYS2.

NOTES: - Only 64-bit versions of Windows 10 and Windows Server 2016 or later are supported and tested. - Make sure you pull with git config --global autocrlf input as windows scripts might not work - Administrative privileges are recommended.


You will need (minimal required): - Visual Studio CLI Build tools (Community Edition 2017+) - Msys2 - Erlang/OTP (20.1 or 20.3 is officially supported) - Java/OpenJDK (11.0.2+)

Note: You might consider easier to use Chocolatey package manager to install the requirements

Install Visual Studio 2019

First you will need to install Visual Studio in its default installation path, else the next steps will fail.

To install only the required components of Visual Studio 2019 Community Edition using Chocolatey run:

> choco install -y visualstudio2019-workload-vctools --params "--add Microsoft.VisualStudio.Component.VC.CLI.Support --locale en-US"

or manually

Download: Visual Studio 2019 Installer

Make sure to include the following components (use the VCTools workload as base):

  • Command-line compiler support
  • Windows 10 SDK

Alternatively you can use vs_buildtools.exe to reduce install size (no GUI).

Note: Visual Studio 2017 Community Edition or later is supported

Quick install of MSYS2, Erlang/OTP, Java

The easiest way to setup the environment is to run scripts/windows/msys2_prepare.bat.

It will install any missing tools to their default locations, except Visual Studio.

If you do so, you may skip to Setup

Custom install of dependencies

Install MSYS2 (optional)

Note: If you don't want to install MSYS2 manually, the preparation script will do it automatically for you.

Else you can use the provided helper script scripts\windows\install_msys2.bat.

It will download and install all the dependencies and will dump the ENV vars used by the build scripts. You may optionally provide installation path as an argument.

The default could be specified in WIN_MSYS2_ROOT env var or fallback to "C:\tools\msys64"

> scripts\windows\install_msys2.bat C:\tools\msys64

Or if you prefer you can install Msys2 using Chocolatey

choco install -y msys2

or manually

Download: MSYS2 Windows Installer

  • Execute installer and follow instructions
  • Keep note of the install folder

Note: You will need to set properly the var (e.g.):

> SET "WIN_MSYS2_ROOT=C:\tools\msys64"

Note: Odd quoting is not a typo

Erlang/OTP 20.3 (optional)

If you don't want to install Erlang/OTP manually, the preparation script will do it automatically for you.

Else you can use scripts\windows\install_erlang.bat.

It will download and install Erlang/OTP and will dump the ENV vars used by the build scripts

> scripts\windows\install_erlang.bat 20.3 C:\tools\erl9.3
SET "WIN_OTP_PATH=C:\tools\erl9.3"

Alternatively you can install Erlang/OTP using Chocolatey

choco install -y erlang --version=20.3

or manually

Download: Erlang/OTP 20.3 Windows Installer

  • Execute installer and follow instructions
  • Keep note of install folder

Note: You will need to set properly the vars (e.g.):

SET "WIN_OTP_PATH=C:\Program Files\erl9.3"

Java Development Kit 11+ (not required)

JDK in no longer essential for building Aeternity and will not be installed by the preparation script.


Now the MSYS2 environment needs to be prepared. This can be done automatically by the helper script scripts/windows/msys2_prepare. It will set the environment variables and download any missing essential tools.

This script uses the following environment variables and default values:

SET "WIN_MSYS2_ROOT=C:\tools\msys64"
SET "WIN_OTP_PATH=C:\tools\erl21.3"

Note: Odd quoting is used to escape any spaces in the values. Make sure paths do not include quotes and trailing slashes.

If your local setup differs, you need to set the proper values yourself before running the preparation script.

It is recommend to persist these vars into the user registry, so you don't need to set it every session, e.g.:

SETX WIN_MSYS2_ROOT C:\tools\msys64
SETX WIN_OTP_PATH C:\Program Files\erl9.3

Note: In contrast of SET, do not put quotes in SETX commands, as they will end up in the values

First time installation

The helper scripts will try to detect where msys2.exe is installed searching WIN_MSYS2_ROOT or the system paths (%PATH%). If the detection fails, install_msys2 script will be used to install it.

Similarly, if Erlang/OTP is missing it will be installed using install_erlang script.

After that script will download, install and update the Msys2 dependencies and tools. Any consecutive runs will check for new updates.

Additional environment config (optional)

Msys2 specific paths can be specified in MSYS_INCLUDE_PATH which are in POSIX(Unix-style) form, separated by ":".

For instance, to add Java in msys2 you have to set the path to its bin directory (the one that includes java.exe)

SET "MSYS_INCLUDE_PATH=/c/Program Files/OpenJDK/jdk-12.0.2/bin:%MSYS_INCLUDE_PATH%"

You can execute the script directly in a cmd window.


Open a MSYS2 shell with the proper paths set.

Use the helper script scripts/windows/msys2_shell.bat to do so.

That script uses the following environment variables (defaults):


In the opened shell (MinGW64) go into your build directory and build the system like on any other UNIX system:


NOTE: Disk drives are mounted in the root folder (i.e. C: is /c)

Note: For a release package build you can use .circleci\windows\build.cmd which will build and produce ready-to-install packages

Refer to docs/ for more information on how to build.