Crash (LogWmfMedia: An error occured when preparing the topology)

Hello, I’m having a problem with my (pure blueprint) VR project: While I preview the game in VR Preview in the editor at some point (after 30 seconds to 2 minutes) the application will crash. I’ve tried deleting Intermediate/Saved folders without success. The project is also building just fine.

The crash reporter is throwing me this:

Unknown exception - code c0000002 (first/second chance not available)

KERNELBASE
mfcore
mfcore
mfcore
UE4Editor_WmfMedia!FWmfMediaTracks::AddTrackToTopology() [d:\build\++ue4+release-4.18+compile\sync\engine\plugins\media\wmfmedia\source\wmfmedia\private\player\wmfmediatracks.cpp:990]
UE4Editor_WmfMedia!FWmfMediaTracks::CreateTopology() [d:\build\++ue4+release-4.18+compile\sync\engine\plugins\media\wmfmedia\source\wmfmedia\private\player\wmfmediatracks.cpp:143]
UE4Editor_WmfMedia!FWmfMediaPlayer::TickFetch() [d:\build\++ue4+release-4.18+compile\sync\engine\plugins\media\wmfmedia\source\wmfmedia\private\player\wmfmediaplayer.cpp:173]
UE4Editor_MediaUtils!FMediaPlayerFacade::TickFetch() [d:\build\++ue4+release-4.18+compile\sync\engine\source\runtime\mediautils\private\mediaplayerfacade.cpp:779]
UE4Editor_Media!FMediaClock::TickFetch() [d:\build\++ue4+release-4.18+compile\sync\engine\source\runtime\media\private\mediaclock.cpp:32]
UE4Editor!FEngineLoop::Tick() [d:\build\++ue4+release-4.18+compile\sync\engine\source\runtime\launch\private\launchengineloop.cpp:3299]
UE4Editor!GuardedMain() [d:\build\++ue4+release-4.18+compile\sync\engine\source\runtime\launch\private\launch.cpp:166]
UE4Editor!GuardedMainWrapper() [d:\build\++ue4+release-4.18+compile\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:134]
UE4Editor!WinMain() [d:\build\++ue4+release-4.18+compile\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:210]
UE4Editor!__scrt_common_main_seh() [f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:253]
kernel32
ntdll

In the log ([crash log - Pastebin.com][1]) I’m also getting the report

[2018.01.17-14.34.22:335][679]LogWmfMedia: Error: An error occured when preparing the topology

a couple of times

I think the problem is related to the Media Player. I have two Media Players with two different videos running in my project. They are shown on four screens and can be toggled by the user. The videos play fine, loop fine, toggle screens just fine. They finish and repeat properly. The blueprints are nothing fancy, they just toggle between the videos (Event Tick is set to 3 seconds to sometimes grab a new video).

Here is the Event Graph and the Construction Script.

Like mentioned before it packages just fine. And from what I’m observing the crash is not appearing in a packaged version (10+ min and me spamming all functions without problem). Unfortunately I will very likely need to present the project in Editor mode, as weird as it sounds.

Any help would be greatly appreciated!

I actually just tested the project locally (since we use a server) with the media files linked to my local SSD, which seems to work. Not 100% sure. But the problem could have been that the files get streamed from the server. It would explain why the packaged project works.

Can you try in 4.19? Thanks!

I´m getting the same crash over and over, any updates? same setup, I have a UI material playing 2 videos (Opaque and Alpha) an both plays at the same time, the crash happens 1/3 of the execs

I know this is an old post, but I found I get crashes and LogWmfMedia: An error occured when preparing the topology (in 4.22.1) when the files that the file media source references is not locally in the Content/Movies folder. Fixing that stopped the crashes for me.