Upgrading to Unreal Engine 4.27#

These instructions apply if you are already using AirSim on Unreal Engine 4.25. If you have never installed AirSim, please see How to get it.

Caution: The below steps will delete any of your unsaved work in AirSim or Unreal folder.

Do this first#

For Windows Users#

  1. Install Visual Studio 2022 with VC++, Python and C#.
  2. Install UE 4.27 through Epic Games Launcher.
  3. Start x64 Native Tools Command Prompt for VS 2022 and navigate to AirSim repo.
  4. Run clean_rebuild.bat to remove all unchecked/extra stuff and rebuild everything.
  5. See also Build AirSim on Windows for more information.

For Linux Users#

  1. From your AirSim repo folder, run 'clean_rebuild.sh`.
  2. Rename or delete your existing folder for Unreal Engine.
  3. Follow step 1 and 2 to install Unreal Engine 4.27.
  4. See also Build AirSim on Linux for more information.

Upgrading Your Custom Unreal Project#

If you have your own Unreal project created in an older version of Unreal Engine then you need to upgrade your project to Unreal 4.27. To do this,

  1. Open .uproject file and look for the line "EngineAssociation" and make sure it reads like "EngineAssociation": "4.27".
  2. Delete Plugins/AirSim folder in your Unreal project's folder.
  3. Go to your AirSim repo folder and copy Unreal\Plugins folder to your Unreal project's folder.
  4. Copy *.bat (or *.sh for Linux) from Unreal\Environments\Blocks to your project's folder.
  5. Run clean.bat (or clean.sh for Linux) followed by GenerateProjectFiles.bat (only for Windows).


I have an Unreal project that is older than 4.16. How do I upgrade it?#

Option 1: Just Recreate Project#

If your project doesn't have any code or assets other than environment you downloaded then you can also simply recreate the project in Unreal 4.27 Editor and then copy Plugins folder from AirSim/Unreal/Plugins.

Option 2: Modify Few Files#

Unreal versions newer than Unreal 4.15 has breaking changes. So you need to modify your *.Build.cs and *.Target.cs which you can find in the Source folder of your Unreal project. So what are those changes? Below is the gist of it but you should really refer to Unreal's official 4.16 transition post.

In your project's *.Target.cs#
  1. Change the contructor from, public MyProjectTarget(TargetInfo Target) to public MyProjectTarget(TargetInfo Target) : base(Target)

  2. Remove SetupBinaries method if you have one and instead add following line in contructor above: ExtraModuleNames.AddRange(new string[] { "MyProject" });

In your project's *.Build.cs#

Change the constructor from public MyProject(TargetInfo Target) to public MyProject(ReadOnlyTargetRules Target) : base(Target).

And finally...#

Follow above steps to continue the upgrade. The warning box might show only "Open Copy" button. Don't click that. Instead, click on More Options which will reveal more buttons. Choose Convert-In-Place option. Caution: Always keep backup of your project first! If you don't have anything nasty, in place conversion should go through and you are now on the new version of Unreal.