Plugin fails to load in 4.18


I am trying to update a plugin to work with 4.18 but am experiencing an issue where the plugin fails to load under conditions.

The packaged executable closes instantly (not even a window is opened) and in the logs is “LogPluginManager: Error: Unable to load plugin ‘PluginName’. Aborting.” with no other information.

The following conditions must all be satisfied for the error to occur:

  • Running Unreal 4.18. In 4.17 it works correctly.
  • The packaged game is being executed. There are no issues opening the editor and running the game in viewport or standalone.
  • The project is blueprint only. If the project contains code there are no issues.
  • The plugin is in the Plugins folder of the project and not installed into the engine Plugins folder. If installed into the engine like a marketplace plugin would be there are no issues.
  • The plugin is the only plugin in the Plugins folder. If there are any other plugins in the Plugins folder, even if they are disabled in the project, the packaged game will run correctly.

Any help appreciated!

I haven’t seen a published branch for 4.18 on their github. Where are you getting this new version?

4.18 was released a few weeks ago

It’s in the release branch on github, but there’s also a 4.18 branch. I’m using the launcher version though.

You have to Build that Plugin from source against the UE4 version you are running (Source or Launcher). If the Plugin Provider supplied you with Binarys for 4.18 than you are fine on the Launcher Version. If you just use the 4.17 ones it won´t work.

Actually I am the provider. The issue described in the OP is concerning the plugin with binaries compiled for 4.18.

Huh. Looking at the source Code right now. It gets to the Point where it definitly knows that it has to load the plugin from the discriptor but but the Find afterwards returns a null pointer. The Question is why its not Loaded even though Binarys are there and the Descriptor seems fine too at that Point.

Wild guess but did you Compile the Binarys for a Shipping Build? Does it work with other Build configurations? Did you find anything in the Package log related to your plugin? And last Question does your plugin come with Source or do you just provide the Binarys?

But it sounds indeed like some strange bug with the Conditions provided (especially the has to be the only plugin one makes no sense to me)

Looks like setting “installed” to true in the .uplugin file fixes this. I have no idea why.