veyon-server doesn't start (Qt::AA_ShareOpenGLContexts must be set before QCoreApplication)

[white_rabbit]

@tobydox
Hi. I enabled the Logfiles in Debug-Mode.
Now I found this:

 /tmp]$ tail  VeyonService.log

2021-05-29T11:52:41.093: [INFO] LinuxServiceCore::startServer(): Starting server for new session "/org/freedesktop/login1/session/_32" with ID 0 at seat "/org/freedesktop/login1/seat/seat0"
2021-05-29T11:55:20.873: [ERR] LinuxServiceCore::startServer(): Can't start Veyon Server in Wayland sessions as this is not yet supported. Please switch to X11-based sessions!
2021-05-29T11:55:23.198: [DEBUG] PlatformSessionManager::closeSession(): Closing session 0 for platform session "/org/freedesktop/login1/session/_32"
2021-05-29T11:55:23.198: [INFO] LinuxServiceCore::stopServer(): stopping server for removed session "/org/freedesktop/login1/session/_32"
2021-05-29T11:55:35.946: [DEBUG] LinuxServiceCore::startServ

When I observe the process veyon-service with catchsegv I found this:

29/05/2021 12:12:03 Xinerama: number of sub-screens: 1
29/05/2021 12:12:03 Xinerama: no blackouts needed (only one sub-screen)
29/05/2021 12:12:03 

X11 MIT Shared Memory Attach failed:
  Is your DISPLAY=:0 on a remote machine?
  Suggestion, use: x11vnc -display :0 ... for local display :0

caught X11 error:
29/05/2021 12:12:03 deleted 32 tile_row polling images.
X Error of failed request:  BadAccess (attempt to access private resource denied)
  Major opcode of failed request:  130 (MIT-SHM)
  Minor opcode of failed request:  1 (X_ShmAttach)
  Serial number of failed request:  57
  Current serial number in output stream:  91

And afterwards the same with veyon-server:

2021-05-29T12:15:35.158: [DEBUG] VeyonCore::initSystemInfo(): "4.5.5" "fossa.my-domain.de" "linux" "5.8.0-53-generic" "Ubuntu 20.04.2 LTS" "ubuntu" "20.04"
2021-05-29T12:15:35.166: [ERR] VncServer::VncServer(): no VNC server plugins found!
2021-05-29T12:15:35.196: [DEBUG] [KLDAP] connection closed!
2021-05-29T12:15:35.196: [DEBUG] [KLDAP] ldap url: "ldap://server.my-domain.de:3268"
2021-05-29T12:15:35.197: [DEBUG] [KLDAP] setting version to: 3
2021-05-29T12:15:35.197: [DEBUG] [KLDAP] setting timeout to: 0
2021-05-29T12:15:35.197: [DEBUG] [KLDAP] setting security to: 1
2021-05-29T12:15:35.197: [DEBUG] [KLDAP] start TLS
2021-05-29T12:15:35.264: [DEBUG] [KLDAP] setting sizelimit to: 0
2021-05-29T12:15:35.264: [DEBUG] [KLDAP] setting timelimit to: 0
2021-05-29T12:15:35.264: [DEBUG] [KLDAP] initializing SASL client
2021-05-29T12:15:35.264: [DEBUG] [KLDAP] binding to server, bindname:  "<MY-SAMBA-DOMAIN>\\admin"  password: *****
2021-05-29T12:15:35.264: [DEBUG] [KLDAP] ldap_sasl_bind_s (simple)
2021-05-29T12:15:35.303: [DEBUG] FeatureWorkerManager::startUnmanagedSessionWorker(): Starting worker (unmanaged session process) for feature QUuid("{8e997d84-ebb9-430f-8f72-d45d9821963d}")
2021-05-29T12:15:35.304: [DEBUG] FeatureWorkerManager::sendMessageToUnmanagedSessionWorker(): User session likely not yet available - retrying worker start
2021-05-29T12:15:35.304: [DEBUG] VncProxyServer::start(): started on port 11100
2021-05-29T12:15:35.304: [DEBUG] VncServer::prepare():
2021-05-29T12:15:35.304: [DEBUG] VeyonCore::exec(): Running
2021-05-29T12:15:35.305: [DEBUG] VeyonCore::exec(): Exit
2021-05-29T12:15:35.305: [DEBUG] ComputerControlServer::~ComputerControlServer():
2021-05-29T12:15:35.305: [DEBUG] VncServer::~VncServer():
2021-05-29T12:15:35.305: [DEBUG] Logger::~Logger(): Shutdown
PluginManager::~PluginManager():
CryptoCore::~CryptoCore():
KLDAP: connection closed!

Is this helpful?

[tobydox]

Can you try to add -noshm as additional custom x11vnc parameter in the advanced VNC server configuration?

[white_rabbit]

@tobydox said in veyon-server doesn't start (Qt::AA_ShareOpenGLContexts must be set before QCoreApplication):

-noshm

Wow -- I think that's the solution! I just added this option and restarted the Client -- now "htop" shows a running veyon-server ... I can't test it in our productive environment at the moment but it looks good so far! Thank you!

[hammergil]

@white_rabbit where do you add this parameter? Is it in the Veyon configuration interface somewhere?

[tobydox]

The VNC server section is correct, make sure to enable advanced view in the menu and to select "Builtin VNC server":

[hammergil]

@tobydox the master computer is running Windows 10 and does not have an option for parameters. The built-in vnc is UltraVNC.

[tobydox]

@hammergil

Since the Linux-based student computers are affected, you have to make the configuration changes on them directly

[hammergil]

@tobydox Great! That did it! Thanks for the help!

[hammergil]

@tobydox what does the parameter "-noshm" mean out of curiosity.

[stephanvaningen]

@tobydox nice. This solved an issue I've been struggling with for quite q few days:) thanks!