Unreal Engine crashes after "Join Session"


so i’m sitting here since about 8 Hours now trying to fix this and finally decided to ask the Community because i really have no Idea anymore.

I’ve implemented the OnlineSubsystemsteam in a Blank C++ Gamemode (working). Now i did copy in the FirstPersonBP which is also “working” (not really, because you can only have one Gamemode at a Time and i dont know how to set the Pawn etc. in C++).

After that i created my Multiplayer “Matchmaking” System. If i press the Button it takes 2-5 Seconds and then the Game crashes. I’m guessing its because of the PlayerController but i have no Idea how to fix it.

Screenshot of the BP:

Error Log:


Access violation - code c0000005 (first/second chance not available)


UE4Editor_OnlineSubsystemNull!TArray<wchar_t,FDefaultAllocator>::CopyToEmpty<wchar_t,FDefaultAllocator>() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\core\public\containers\array.h:2263]
UE4Editor_OnlineSubsystemNull!FOnlineSessionNull::JoinLANSession() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\online\onlinesubsystemnull\private\onlinesessioninterfacenull.cpp:675]
UE4Editor_OnlineSubsystemNull!FOnlineSessionNull::JoinSession() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.8\engine\source\runtime\online\onlinesubsystemnull\private\onlinesessioninterfacenull.cpp:584]

(there more Lines but i guess you just need those)

One more Notation: It also crashes when i play it in Standalone Modus etc.

Well its still happening.

Hey! Hope by now you’ve found a solution but in an effort to leave no question unanswered, I’m gonna post what I think might be wrong with your set up. Just yesterday I was messing around with networking, however I was using OnlineSubSytemNull so I don’t think I can evaluate your code too well. In blueprint, there’s two things that are standing out to me.

The first being that you’re not checking to see if there’s any element in your array of games to join. This is what’s likely causing your crash. Though that would also means that your host game call is also failing in some way. Take a look at this [link][1] since you’re using a C++ project. Because you’re using Steam, also make sure that Steamworks is properly running and you’re online in Steam. That might help with that.

The second isn’t related to your crash but even if you did had everything working properly you wouldn’t see another player in your map. This is because UE4 needs to be told to open up sockets which it can do when a map is loaded.

Check out my setup. Again, this is for OnlineSubSystemNull but as far as blueprints go, it shouldn’t matter since it’s meant to be generalized.