# Client disconnecting crashes Server, pls help!

**URL:** <https://forums.unrealengine.com/t/client-disconnecting-crashes-server-pls-help/2855746>\
**Category:** Issues and Bug Reporting (Unreal Engine)\
**Tags:** Steam, unreal-engine, Multiplayer, bug-report, question\
**Created:** [November 14, 2026, 7:57am UTC](https://forums.unrealengine.com/t/client-disconnecting-crashes-server-pls-help/2855746 "2026-11-14T07:57:52Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![HelioHsx](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@HelioHsx](https://forums.unrealengine.com/u/HelioHsx)\
**Post date:** [November 14, 2026, 7:57am UTC](https://forums.unrealengine.com/t/client-disconnecting-crashes-server-pls-help/2855746/1 "2026-11-14T07:57:52Z")

</div>

### Summary

Hello,  
I am using 5.6 and got the advancedsteamsessions plugin, also using steam sockets. I have a packaged multiplayer game where the connections and logic all work, but the moment a client disconnects: server/host gets this error “MappedClientConnections.Remove(ConstAddrRef) == 1” and crashes, thus crashing the clients too.

It seems this issue is known and I still haven’t found a solution.

Would appreciate any help!

### What Type of Bug are you experiencing?

Online

### Steps to Reproduce

5.6  
Have advancedsteamsessions plugin  
Have steam sockets plugin  
Host packaged game with steam open in background  
Join game from another steam account using the “join game” in steam friends overlay  
Quit game, exit or alt f4 from the client

### Expected Result

Client disconnecting shouldnt crash server.

### Observed Result

Client disconnecting freezes and crashes server instantly.

### Affects Versions

5.6

### Platform(s)

Windows

### For crash reports, include your callstack

[12:43:26.819] SteamSockets: Now tracking socket [SOCKET\_A] for addr [STEAM\_ID]:7777  
[12:43:26.820] NotifyAcceptedConnection: [CONNECTION\_A], PC: NULL, UniqueId: INVALID  
[12:43:26.820] AddClientConnection: Added client connection [CONNECTION\_A]

[12:43:26.942] SteamSockets: Now tracking socket [SOCKET\_B] for addr [STEAM\_ID]:7777  
[12:43:26.942] NotifyAcceptedConnection: [CONNECTION\_B], PC: NULL, UniqueId: INVALID  
[12:43:26.942] AddClientConnection: Added client connection [CONNECTION\_B]

[12:43:27.384] SteamSockets: Socket [SOCKET\_B] connected

[12:43:27.522] SteamSockets: Socket [SOCKET\_A] closed by peer  
[12:43:27.551] UNetDriver::RemoveClientConnection:  
Removed address [STEAM\_ID]:7777 for [CONNECTION\_A]  
[12:43:27.551] UNetConnection::PendingConnectionLost:  
[CONNECTION\_A], PC: NULL, UniqueId: INVALID

[12:43:27.683] SteamSockets: Connectionless handshake complete  
[12:43:28.127] LogNet: Join succeeded: [PLAYER]

[12:43:45.946] SteamSockets: Socket [SOCKET\_B] closed by peer  
[12:43:45.957] UNetDriver::RemoveClientConnection:  
Removed address [STEAM\_ID]:7777 for [CONNECTION\_B]

[12:43:45.961] ASSERTION FAILED:  
MappedClientConnections.Remove(ConstAddrRef) == 1  
Engine/Source/Runtime/Engine/Private/NetDriver.cpp  
Line: 6918