[4.8.1] Audio crash after C++ hot-reload

Development Audio
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41

I’m really interested into a solution on this also.
We have multiple people complaining about the same issue here:

Does someone have test on 4.9 preview if the issue has been resolved?

42

Hey guys, sorry for the trouble!

We’re unable to reproduce the issue on 4.8 and we suspect the problem is likely fixed in upcoming 4.9 release but because we can’t repro the problem, we’re not 100% sure.

If somebody who is experiencing the hotload crash could try to repro on the 4.9 preview branch, that’d be extremely helpful. We’re still finding/fixing 4.9 bugs so if you find it there, we can jump on it and maybe get a fix before 4.9 releases.

Link to Github 4.9 preview branch

Link to info about the 4.9 preview

43

Tried the 4.9.0 preview 1 from the launcher and still got the crash after a hot-reload.

I did not start up the engine through VS debug mode, I attached the crashlog.

~Per “” Johansson

44

Interesting – the only way that assert can fail is if a source is getting created after the main audio device was shutdown. What are your exact repro steps? I’d like to see if I can capture a repro before trying to make a speculative fix.

If this bugging you to no end, you’re welcome to attempt a possible fix (since we don’t have an internal repro for this issue) by returning false instead of asserting the audio device object was found:

Change line 447 from:

check(BestAudioDevice);

To:

if (!BestAudioDevice)
{
    return false;
}

If the sound source fails to init, then the UE4 will continue on without crashing. My current (untested theory) is this crash is from an editor UI sound being played outside of the normal path for sounds to play and is playing a sound in-between the audio device getting shutdown and set back up after a hot reload.

45

As I’ve said earlier. I don’t do anything special.

  1. Start the project in DebugGame Editor Win64 in VS
  2. Start PIE session without problems
  3. Stop PIE session
  4. Change to VS and only change a single character (press space then backspace in any file) to trigger a code version mismatch.
  5. Click recompile button in-editor
  6. Wait for recompile to complete
  7. Start PIE session.
  8. Crashes on any SFX (music is fine) that’s played on that assert.

This bug appears to be fixed in the 4.10.0-0+UE4 version on the Unreal Engine master branch on GitHub.

~Per “” Johansson

46

Hey -

We’ve submitted a bug report for this crash to see if we can track down the cause(UE-19563). Please let us know if this crash is still affecting after the next version release however the best solution for the time being would be to close the editor when compiling to avoid any issues with the hot reload.

Cheers

47

I updated to the pre-release version 4.9.0-2641355+++depot+UE4-Releases+4.9 through the launcher and the bug seems to be fixed. I’ve hot-reloaded multiple times now, PIE and have had numerous sounds being played without a problem.

Thank you!

~Per “” Johansson

48

Excellent news… I’m curious what changed between the two versions.

49

I don’t know if I did something wrong when testing preview 1,. but I previously mentioned that when I tested the preview 1 of 4.9 I didn’t start up the editor through VS. This was due to an error (which I noticed today was caused by not setting the project as the startup project in VS…)

Instead I dragged and dropped the .uproject-file on the UE4Editor.exe to force open the project…but I don’t think that would roll back the engine to the 4.8 version since the about page in-editor said 4.9 when I checked then.

I don’t know if it really mattered or not, but I thought you’d like to know.

~Per “” Johansson