[T5MP] Dedicated server loops "SESSION CREATE ERROR 2103" (BD_INVALID_SESSION_ID) heartbeat OK, DW auth OK

[snrgabe]

Setup
T5MP dedicated server r5334 on Linux (Debian, Wine 9.0, Docker), game files from my own Steam copy (app 42700, Windows depot). Launched via:

bin/plutonium-bootstrapper-win32.exe t5mp /path/to/Server/ -dedicated +set key XXX +set fs_game "" +set net_port 21892 +exec dedicated.cfg +map_rotate

The server boots fine: fastfiles load, dedicated.cfg execs, map rotation set, DW auth completes (DW_AUTHORIZED -> DW_LOGON_COMPLETE), and heartbeats succeed. But it endlessly loops:

Parsed 0 reserved slot passwords
SESSION CREATE ERROR 2103
Session creation failed. Killing server
MATCHMAKINGDEBUG: Calling updatesession...
Server: Updating session - serverinfo change
Session update error!

---

RECREATING SESSION

---

reauthenticating dedicated server!
DW_AUTHORIZED -> DW_LOGON_COMPLETE
SESSION CREATE ERROR 2103 (repeats forever)

2103 = 0x837 = BD_INVALID_SESSION_ID.

Already tried:

• Fresh server key created specifically for T5MP (not reused from another game)
• Removing all custom dvars from the launch line
• Fresh Plutonium files via plutonium-updater (r5334)

A T6MP server on the same host/network works perfectly (heartbeat, listing, players joining), so outbound connectivity and NAT are fine. Game UDP port is forwarded.

Is error 2103 on session create a known backend issue for T5MP dedis (similar to the old T5SP session errors), or is there something server-side I should check? Does this affect joinability/listing, or is it safe to ignore?

[Fusions5]

Did you come up with any solutions? I'm facing the exact same issue and the server does not appear. Just a short time a go everything was working fine. (r5344)

[letgetmcdonald]

I am also getting the exact same issue on Debian 12 and have also verified that T6MP works perfectly on the same machine.

Using the same server key on a Windows install worked fine in the past which indicated a possible Linux/Wine issue but I am yet to confirm if it works. Another post did say they got the same issue on Windows and considering T6 works fine on the exact same machine with Debian 12 makes me doubtful it is purely a Linux issue.

I have done extensive troubleshooting and can't see any way forward without support from the Devs.