fmodL.dll crashes the game on UE4.26

Hello, we are upgrading our project currently from UE4.24 to UE4.26. We are experiencing a problem where fmodl.dll crashes the game in the main menu.
Sometimes it happens when you click a button - other times it happens when you are moving your mouse. Sounds and music are playing just fine.

A few things to note:

  1. This exception did not exist in FMOD for UE 4.24
  2. As a test, we used the 4.25 dll’s and we got the same error.
  3. It ONLY happens with packaged versions (both development and shipping builds) - it never happens in the editor.

Turns out, disabling logging fixes it. It also gets fixed by delaying the loading of the master bank.

Also having this problem upgrading to 4.26. This crashes dedicated servers on startup once it loads a map as well.

We’re also seeing something similar happening on level switching since upgrading to 4.26. We’ve seen it happening on XSX with the following message: Crash in fmodl.dll : “Access violation reading location 0x00007FFF9EA275C8”

Something else I noticed, when I recompile fmod (Delete binaries/intermediates but leave all .lib) I never get new fmod.dll’s just UE4Editor-FMODStudio.dll (and pbd). All the dll’s in the fmod ue4.26 zip with libs have DLLs dated 2/10/2021 and I wonder if they’re outdated since they don’t recompile?

I built development editor, development and shipping and did not get new dll’s in Game/Plugins/FMODStudio/Binaries/Win64/

Thanks for reporting this issue, we’ll investigate and release a fix as soon as possible.

The FMOD dll’s are binaries produced by building our proprietary source code and cannot be rebuilt unless you have a source license. If you’ve deleted them from the binaries folder you’ll need to restore them from the distributed package.

Ah ok. I did restore but do get a crash in fmodL.dll every map launch on dedicated server.

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Thanks for clarifying - presumably it’s the same issue so hopefully we can find a fix for that soon.

If I had to guess, seems so. Maybe a race condition or something with that “first tick” load call expecting something to already be available or something of that nature. I have a rar file with a crash log, dmp and exe/pdb if I could privately get it to you or someone at FMOD.

Sry I checked my logs its fmodstudioL.dll but I have seen logs also say fmodL.dll as well

If you’re able to upload logs and a crash dump using the Uploads tab on the user profile page at that would be very helpful.

I DM’d you a drive link while I wait on permissions to upload in that section.

Thanks @mpactmatt, there’s a null pointer dereference in your crash dump and I’ve added it to our tracker to be fixed asap.

I’m not entirely certain whether this is the same issue as others are reporting in this topic, and I haven’t had any luck reproducing the issue myself yet, so I’ll leave the topic open for now and once the fix for the null dereference bug in your crash dump is released we can see if the issue is fixed for everyone.

Would it be possible to get me an updated fmodL.dll to help test if the fix was successful before the full drop?

The fixes we need to make are in the UE4 plugin, not in the FMOD libraries, so there won’t be an updated fmodL.dll for this - we will push the fixes to the plugin to GitHub once they’re done though (and the official release should be close behind that).

Is there a rough timeline on this fix? Just for planning/scheduling purposes. This is a total blocker for us patching, updating, testing any multiplayer functionality but I understand triaging/other issues at hand, just want to plan.

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I can’t promise anything to concrete, unexpected problems are always unexpected, so take this with a grain of salt, but it should be available very soon from GitHub, and in an official release shortly after that. We’ve developed a fix which is going through code review now. I’ll push the fix to GitHub as soon as it’s past code review, and then we’re pushing to get our release out this week.

The fix has passed code review and has now been pushed to GitHub.

Have confirmed that it has fixed our dedicated server crash! Thank you for your diligence and speed on this @Derek_Burnheim and any other engineers involved. It is greatly appreciated!

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Glad to hear it, thanks for confirming!