How to Fix an FRunnable Thread Not Stopping on Shutdown in Unreal

Your background FRunnable polls a queue forever. At shutdown the editor or game hangs because the Run loop never noticed it should stop. You must signal and join it. Here is how to wire that up.

How to fix it

1. Check an atomic stop flag

In Run(), loop while (!bStopRequested) { ... } using a FThreadSafeBool or std::atomic<bool> so the flag is visible across threads.

2. Set the flag in Stop()

Implement Stop() to set bStopRequested = true and wake the thread if it is blocked on an event, so the loop can break out.

3. Kill with wait, then delete

Call Thread->Kill(true) to set the flag and block until the run loop returns, and only then delete the runnable and the thread object.

Catching the ones you can't reproduce

The hardest version of this to fix is the one you can't reproduce — it only happens on a player's hardware, OS, driver, or save state, under conditions that simply aren't present on your machine. A report that says “it crashed” or “it froze” gives you nothing to act on, so the bug survives release after release while quietly costing you players.

Automatic error capture closes that gap. Each failure arrives with its full stack trace, the device and OS, the build number, and a breadcrumb trail of what the player did right before it broke, so even a failure you have never seen becomes a specific, reproducible issue. Fold identical failures into one signature ranked by how many players each hits, and your worklist sorts itself worst-first instead of arriving as a stream of vague complaints.

This is where a tool like Bugnet earns its place. Its SDK captures every Unreal Engine error automatically with the full stack trace plus device, OS, memory, build, and game-state context, folds duplicates into one grouped issue with an occurrence count, and ties each to the build it first appeared on — so you fix the problem that hurts the most players first and confirm it is gone when its signature disappears from the next release.