Error Assertion failed: Package != nullptr UE_5.0

I following a course about creating a multiplayer c++ game using the steam subsytem and seamless travel. I have packaged a build to test multiplayer connection, Players are able to host and join a lobby but when the server tries to seamless travel to the next map i get this error. Any tips or information will be extremely helpful!

Assertion failed: Package != nullptr

0x00007ff6dcd3122b MPShooter.exe!ForEachObjectWithPackage() []

0x00007ff6dcd36a35 MPShooter.exe!GetObjectsWithPackage() []

0x00007ff6e1f36c13 MPShooter.exe!FSeamlessTravelHandler::SeamlessTravelLoadCallback() []

0x00007ff6e1f21247 MPShooter.exe!TBaseRawMethodDelegateInstance<0,FSeamlessTravelHandler,void __cdecl(FName const & __ptr64,UPackage * __ptr64,enum EAsyncLoadingResult::Type),FDefaultDelegateUserPolicy>::ExecuteIfSafe() []

0x00007ff6dca67748 MPShooter.exe!FAsyncLoadingThread2::ProcessLoadedPackagesFromGameThread() []

0x00007ff6dca859b2 MPShooter.exe!FAsyncLoadingThread2::TickAsyncLoadingFromGameThread() []

0x00007ff6dca6a7f1 MPShooter.exe!FAsyncLoadingThread2::ProcessLoadingFromGameThread() []

0x00007ff6dca692f7 MPShooter.exe!FAsyncLoadingThread2::ProcessLoading() []

0x00007ff6dcab6881 MPShooter.exe!ProcessAsyncLoading() []

0x00007ff6e159b632 MPShooter.exe!UWorld::Tick() []

0x00007ff6e13cae3c MPShooter.exe!UGameEngine::Tick() []

0x00007ff6dada5507 MPShooter.exe!FEngineLoop::Tick() []

0x00007ff6dadbce5c MPShooter.exe!GuardedMain() []

0x00007ff6dadbcf2a MPShooter.exe!GuardedMainWrapper() []

0x00007ff6dadbffac MPShooter.exe!LaunchWindowsStartup() []

0x00007ff6dadd1764 MPShooter.exe!WinMain() []

0x00007ff6e2ff5c3a MPShooter.exe!__scrt_common_main_seh() [d:\a01_work\43\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:288]

0x00007ffd8c217034 KERNEL32.DLL!UnknownFunction []

0x00007ffd8c5a2651 ntdll.dll!UnknownFunction []

Have You find any solution because i also got the same error .

1 Like

If anyone is still struggling with this error during seamless travel.
Make sure to unload any loaded streaming levels in your persistent level before initiating seamless travel. This approach resolved the issue for me.

Hope this helps!