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Question Unreal Multiplay server crashing

Discussion in 'Game Server Hosting' started by maria-marshmallow, Feb 15, 2023.

  1. maria-marshmallow

    maria-marshmallow

    Joined:
    Jan 26, 2023
    Posts:
    3
    Hi there,

    I'm having some issues getting my server spun up. Wondering if anyone can lend advice

    I'm using the Multiplay Linux SDK with an Unreal 5.1 dedicated server project, compiling to a Linux build.

    The issues I'm encountering are
    * Cannot see server logs on the Multiplay dashboard
    * Server crashes moments after startup

    My launch parameters are set like so:
    -port=$$port$$ -LOG=../../../../$$log_dir$$/$$serverid$$.log -queryPort $$query_port$$ -queryType $$query_type$$


    The server crash -
    server crash.png

    And these are the blueprints which live inside the game (server) map - so not in the entry (client) map -
    dedicated server blueprint.png

    Best,
    Maria
     
    maria-marshmallow, Feb 15, 2023
    #1

  2. ajdaniel_unity

    ajdaniel_unity

    Unity Technologies

    Joined:
    Jul 19, 2019
    Posts:
    22
    To fix the missing logs you should change your build configuration flag:

    ```-LOG=../../../../$$log_dir$$/$$serverid$$.log```

    should be:

    ```-logFile=$$log_dir$$/$$serverid$$.log```.

    I'm not familiar with the visual coding you are using there, someone else might be, but the Query DOWN log messages seem to indicate that you haven't initialised SQP at server startup. Try the change above which might give you some log messages to follow and report back if you need more help
     
    ajdaniel_unity, Feb 15, 2023
    #2

  3. ajdaniel_unity

    ajdaniel_unity

    Unity Technologies

    Joined:
    Jul 19, 2019
    Posts:
    22
    My apologies, I was assuming you were using the Unity engine for your game. My instructions for the log path are, therefore, incorrect.

    Instead, I recommend you take a look at this documentation page https://docs.unity.com/game-server-hosting/en/manual/guides/redirect-logs-for-unreal-games for setting up logs for Unreal engine games, and this video for further guidance:


    I apologise for providing incorrect advice and I hope this new advice can help you. Feel free to reach out once more if you have questions or queries
     
    ajdaniel_unity, Feb 15, 2023
    #3

  4. maria-marshmallow

    maria-marshmallow

    Joined:
    Jan 26, 2023
    Posts:
    3
    Hey thanks for the suggestion, sadly 
    -logFile=$$log_dir$$/$$serverid$$.log
    doesn't produce logs either

    For the launch parameters I followed these instructions https://docs.unity.com/game-server-hosting/en/manual/concepts/launch-parameters#Unreal

    Wondering how to initialise SQP at server startup as you suggest. I haven't created any Server Query Handler Subsystem nodes yet so will try that. (You mentioned you're not familiar with Unreal blueprints so putting this here in case anyone else can pick it up)

    I didn't include a screenshot of the Server Config Subsystem blueprint, here it is.
    server config sybsystem.png
     
    maria-marshmallow, Feb 15, 2023
    #4

  5. maria-marshmallow

    maria-marshmallow

    Joined:
    Jan 26, 2023
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    Thanks for reminding me about the above tutorial, I now have the logs!

    -port=$$port$$ -queryPort=$$query_port$$ -log=../../../../..$$log_dir$$ENGINE.log
    is the correct way to format the launch parameters.

    Have attached the log.

    Specifically some time after the engine initialisation I see a fatal error. I can confirm that this build runs successfully locally.

    Code (csharp):
    1. [2023.02.15-16.55.03:676][  0]LogLoad: (Engine Initialization) Total time: 2.77 seconds
    2. [2023.02.15-16.59.02:090][132]LogCore: === Critical error: ===
    3. Unhandled Exception: SIGSEGV: invalid attempt to read memory at address 0x0000000000000000
    4.  
    5. [2023.02.15-16.59.02:091][132]LogCore: Fatal error!
    6.  
    7. 0x00007f028af2123f libc.so.6!clock_nanosleep(+0xdf)
    8. 0x00007f028af26ec7 libc.so.6!nanosleep(+0x16)
    9. 0x00007f028af5985f libc.so.6!usleep(+0x4e)
    10. 0x0000000009c4b174 STREAMServer-Linux-Debug!
     

    Attached Files:

    maria-marshmallow, Feb 15, 2023
    #5

  6. Sean15_Unity

    Sean15_Unity

    Unity Technologies

    Joined:
    Aug 19, 2022
    Posts:
    4
    Hey @maria-marshmallow It looks to be a Memory read error as shown

    This message usually indicates that an unhandled exception has occurred during game server run. Looking further, we see "SIGSEGV" is the core error, this indicates that it is caused by an invalid attempt to write to memory

    This could occur from multiple reasons, being a possible stack corruption, a buffer overflow happening in the game code, or a null pointer reference; what I mean by these, is that somewhere in your program, it is trying to access a memory location that it shouldn't be accessing - potentially causing by a bug in the program.

    I'd recommend checking over your code for any bugs, the Unreal forums themselves could also assist with this error.
     
    Sean15_Unity, Mar 6, 2023
    #6

  7. erebel55

    erebel55

    Joined:
    Jun 14, 2014
    Posts:
    43
    Hey @maria-marshmallow, we are also running into this exact same crash on Unreal 5.1, multiplay linux dedicated servers. Although our servers crash randomly during a match and only sometimes, so it isn't a boot crash for us. Were you able to resolve the issue or have any other insight that would be helpful?
     
    Last edited: Apr 26, 2023
    erebel55, Apr 26, 2023
    #7