UE4.16 server travel crash

Hi,

I’am experiencing crash in my project(packaged build) on UE4.16 during servertravel exactly when the server re-travel on an already loaded level with this error message :

227382-capture.jpg

I have tried to copy the part of the code from the 4.18 on github in the AsyncLoading.cpp into the 4.16 source code.
That did the tricks for a while and we were able to load back a level without any problems but sometimes the engine crashed again only when we are using servertravel this time no matter if we have already loaded the level or not :

227385-crash.jpg

The project was developped at the beggining on UE4.12 and I have migrated it to the UE4.16 version were we are finaly experiencing the servertravel issue.

After all of this I have tried to migrate the project from 4.16 to the 4.18 version but now the game is randomly freezing without any messages, logs or error message like an infinite loop.

ps : everything happend on packaged game ( debug, or shipping ) and it’s a multiplayer game ( not dedicated server , in LAN ).

Regards,

OximusPrime.