When I build from source using the “Development Editor” configuration, everything works fine. I can launch and debug with no errors. However, when I change the solution configuration to “DebugGame Editor”, the build succeeds, but when I launch from Visual Studio or from the built UE4Editor, I get the error: “Plugin ‘OnlineSubsystem’ failed to load”.
My intent was to work on a game with the engine running optimized code at times, using the “DebugGame Editor” configuration, and switching to “Development Editor” when I want to debug the engine code.
Based on other threads, this seems to be related to the Steam SDK. Since this is the engine build from source, I also don’t know where I could disable the plugin, as one possible solution.
For now, I can just stick with the “Development Editor” configuration, but it would be nice to know what’s going on.