Startup Movie crash

Hi,
After we upgraded to 4.21 we are seeing more people crashing during startup, seems to be related to intro videos.

This is the crash log:

FWebMContainer::Open() [c:\p4\unrealengine\main4-21\engine\plugins\media\webmmedia\source\webmmedia\private\webmcontainer.cpp:36]
    FWebMMovieStreamer::StartNextMovie() [c:\p4\unrealengine\main4-21\engine\plugins\runtime\webmmovieplayer\source\webmmovieplayer\private\webmmoviestreamer.cpp:87]
    FDefaultGameMoviePlayer::PlayMovie() [c:\p4\unrealengine\main4-21\engine\source\runtime\movieplayer\private\defaultgamemovieplayer.cpp:347]
FEngineLoop::PreInit() [c:\p4\unrealengine\main4
21\engine\source\runtime\launch\private\launchengineloop.cpp:2290]

We also had some crashes on 4.19 on startup that seemed related to intro movie (different callstack), but those where less frequent and have gone away.
At least one user was able to get the game working by deleting the movie files.
Any idea what the problem could be related to? Bad Codec, corrupted files? (We cannot reproduce the issue here)

Cheers!
Jonas

So we dug a little deeper and our theory is that this crash happens when UE fails to load the normal movie players. It then defaults to the WebMovieStreamer. However it is looking for .webm files, which we dont have so it fails, but not in a good way:

bool FWebMMovieStreamer::StartNextMovie()
{
	if (MovieQueue.Num() > 0)
	{
		ReleaseAcquiredResources();

		MovieName = MovieQueue[0];

		MovieQueue.RemoveAt(0);

		FString MoviePath = FPaths::ProjectContentDir() + TEXT("Movies/") + MovieName + TEXT(".webm");

		if (FPaths::FileExists(MoviePath))
		{
			Container.Reset(new FWebMContainer());
		}
		else
		{
			UE_LOG(LogWebMMoviePlayer, Error, TEXT("Movie '%s' not found."));
                    <Missing return false>
		}

		UE_LOG(LogWebMMoviePlayer, Verbose, TEXT("Starting '%s'"), *MoviePath);

Seems like there should be a return false in the if/else clause where it checks if the moviepath exists.

We will try this change and see if it fixes the issue.

Hello,

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Thanks

new or old reporting form, is this fixed? 4.21 crashes relentlessly on mac, even if linking a 500kb startup movie in mp4.

this is super frustrating. especially since Unreal doesnt recognize .webm files, at least on 4.21 / OSX, where I tested it.