C++ classes disappear after restart

It’s pretty confusing, I’m using UE 5.2.1 and when I restart the project, every C++ class I’ve made is gone. Is anyone else experiencing the same issue?

I have had this happen to me. There’s a few things I do when this or something fishy in general is happening with c++. I’ll try and list them like a Haynes Manual, sorted by easiestToFIx/mostCommon.


Try and stick to BluePrint when possible. BluePrints just work without fiddle’n. (except fiddle’n with all those damn noodles everywhere! lol. Fingers crossed for Verse)

LiveCoding/HotReload: That button in the bottom right of the editor

Opinions are mixed on this feature, but I like it bc it’s faster and it’s gotten better. The most common pitfall to avoid is LC seems to break if you make changes to the .h file, it’s fine for .cpp changes most of the time.
To Fix: SAVE! then save and Close the editor. Open either the .uproject or .sln with the IDE. Build in IDE. Launch the game from IDE.
Note: ensure the IDE is using the Development build (or Debug if you have Debug set up).

Refresh UProject:

Within Editor at the top, Tools > Refresh Uproject

Where did my environment art go?:

Close project and IDE. Open the project from the epic launcher. Hit the compile button(bottom right in editor). Within Editor at the top, Build > Build All Levels.
Note: depending on your experience with UE, you may want to skip building HLODs if using an open world

Compiler errors or actual problem solving:

Try opening the file to look for the errors, sometimes just opening the file fixes it.
Read it and fix it. General debugging workflow and deal with frustration. Get help with Chat-gpt, forums, Google, Discord, Common Issues, etc. Logs can be found in YourProject/Saved/Logs/ as well as listed in the IDE. If this takes more than 30 min, skip it and come back.

Generate VS Project files:

Close the eidtor and IDE. Navigate to the project in file explorer. Delete the folders [Binaries, Intermediate]. Right click the .uproject and Generate VS Project files. Open either the .uproject or .sln with the IDE. Build in IDE. Launch the game from IDE.
NOTE: Additional folders can be deleted (do some research first). [Binaries, Intermediate, Saved, .sln, DerivedDataCache, .vs(or .idea, xcode, VScode, the IDE folder), Build, Plugins//Intermediate]. Also the contents of user/AppData/UnrealEngine folder can be deleted.
Would sb offer some feedback on deleting folders

Workloads and Versions

Double check you set up all your Workloads for your version of UE. As well as the Release Notes > Platform SDK info

Unskip Compiler errors, if you skipped them.

Version Control:

Don’t checkout with uncommitted changes. Go back to a working commit.

Dumb Stuff

Don’t use privileged folders like Program Files. Don’t use special Characters. If multiplayer, simulate lag. There’s some good pinned messages on Unreal Slackers/Source’s Discord in the cpp server. Read the source code on github, look at sample projects, read the UE docs as well as “unofficial UE docs”. Get a library card for books, LinkedIn Learning, Udemy, etc., whatever your library supports.

I’m a caveman and this works for me, but fell free to give any and all feedback for anything I said. I’ve been needing to organize my thoughts about this, I’m happy I wrote a text wall compared to OP’s simple question.

Sticking with Blueprint - This doesn’t really work for everything and particularly needs C++ for multiplayer and the likes.

Try turning off live coding completely and again, as you’ll see many times over, delete binaries and intermediate folder. Launching will then rebuild your changes.

Classes disappearing often happens with Live coding on but it may not solve it. Saying that, in the last few weeks it has fixed things for a number of students.

run your MultiplayerCourseEditor win64 development build on your C++ editor.

Whenever I open my C++ projects I always run that build task and then also click on the live code compiler

This type of behaviour is why Kaan goes through the process of closing the editor, deleting the intermediate folder, and rebuilding the project. This is a side-effect of using Hot Reload or Live Coding.

Alternatively, you can just close the unreal editor and in Visual Studio Community select Rebuild Solution

Yeah. My workflow is to start UE by building it from Visual Studio. When I want to make code edits I first close the Unreal Editor. It’s been much more stable than Live Coding.

This is one of the more frustrating aspects of Unreal. It’s one of the reasons why working with blueprint has serious advantages.

But once you have the basics established, it seems to work well.

Privacy & Terms