Matlab 2023b WebApp error message on Ubuntu 22.05 web server

I'm trying to make my webApp working.

1. Menu does run
2. After setting up parameters and start performing simulations, I'm getting following error message:

WebSockets protocol was not established. This may cause performance degradation and occasional errors. Contact your System Administrator.

2024-02-09 16:54:52 New session requested for "PREDICT_GUI"

2024-02-09 16:54:56 Session for "PREDICT_GUI" created successfully

2024-02-09 16:55:26 ctfxlauncher: <unknown>:0: <unknown>: Assertion `QFontDatabase: Must construct a QGuiApplication before accessing QFontDatabase' failed.

2024-02-09 16:55:26 --------------------------------------------------------------------------------

2024-02-09 16:55:26 Assertion detected at 2024-02-09 16:55:26 +0100

2024-02-09 16:55:26 --------------------------------------------------------------------------------

2024-02-09 16:55:26 Configuration:

2024-02-09 16:55:26 Crash Decoding : Disabled - No sandbox or build area path

2024-02-09 16:55:26 Crash Mode : continue (default)

2024-02-09 16:55:26 Default Encoding : UTF-8

2024-02-09 16:55:26 Deployed : true

2024-02-09 16:55:26 GNU C Library : 2.35 stable

2024-02-09 16:55:26 Graphics Driver : Uninitialized software

2024-02-09 16:55:26 Graphics card 1 : 0x102b ( 0x102b ) 0x522 Version 0.0.0.0 (0-0-0)

2024-02-09 16:55:26 Java Version : Java 1.8.0_202-b08 with Oracle Corporation Java HotSpot(TM) 64-Bit Server VM mixed mode

2024-02-09 16:55:26 MATLAB Architecture : glnxa64

2024-02-09 16:55:26 MATLAB Entitlement ID : Unknown

2024-02-09 16:55:26 MATLAB Root : /usr/local/MATLAB/MATLAB_Runtime/R2023b

2024-02-09 16:55:26 MATLAB Version : 23.2.0.2459199 (R2023b) Update 5

2024-02-09 16:55:26 OpenGL : software

2024-02-09 16:55:26 Operating System : Ubuntu 22.04.3 LTS

2024-02-09 16:55:26 Process ID : 689079

2024-02-09 16:55:26 Processor ID : x86 Family 6 Model 63 Stepping 2, GenuineIntel

2024-02-09 16:55:26 Session Key : 6acf47ee-2ef1-4afd-943c-9d826b6eae04

2024-02-09 16:55:26 Window System : No active display

2024-02-09 16:55:26 Fault Count: 1

2024-02-09 16:55:26 Assertion:

2024-02-09 16:55:26 QFontDatabase: Must construct a QGuiApplication before accessing QFontDatabase

2024-02-09 16:55:26 Current Thread: 'MCR 0 interpret' id 140184645531200

2024-02-09 16:55:26 Register State (captured):

2024-02-09 16:55:26 RAX = 0000000000000000 RBX = 00007f7fdefef2c8

2024-02-09 16:55:26 RCX = 0000000000000000 RDX = 00007f7fdefe8eb0

2024-02-09 16:55:26 RSP = 00007f7f47ff0d30 RBP = 00007f7f47ff1110

2024-02-09 16:55:26 RSI = 00007f7fdefcf025 RDI = 00007f7f47ff0d40

2024-02-09 16:55:26 R8 = 0000000000000000 R9 = 00007f7f47ff1020

2024-02-09 16:55:26 R10 = 0000000000000000 R11 = 0000000000000000

2024-02-09 16:55:26 R12 = 00007f7fdefff348 R13 = 00007f7f47ff15d0

2024-02-09 16:55:26 R14 = 00007f7f47ff1170 R15 = 0000000000000000

2024-02-09 16:55:26 RIP = 00007f7fdef7dd1f EFL = 0000000000000000

2024-02-09 16:55:26 CS = 0000 FS = 0000 GS = 0000

2024-02-09 16:55:26 Stack Trace (captured):

2024-02-09 16:55:26 [ 0] 0x00007f7fdef77063 /usr/local/MATLAB/MATLAB_Runtime/R2023b/bin/glnxa64/libmwfl.so+00319587

2024-02-09 16:55:26 [ 1] 0x00007f7fdef7725c /usr/local/MATLAB/MATLAB_Runtime/R2023b/bin/glnxa64/libmwfl.so+00320092 _ZN10foundation4core4diag15stacktrace_base7captureEm+00000028

2024-02-09 16:55:26 [ 2] 0x00007f7fdef799f8 /usr/local/MATLAB/MATLAB_Runtime/R2023b/bin/glnxa64/libmwfl.so+00330232

2024-02-09 16:55:26 [ 3] 0x00007f7fdef7a662 /usr/local/MATLAB/MATLAB_Runtime/R2023b/bin/glnxa64/libmwfl.so+00333410

2024-02-09 16:55:26 [ 4] 0x00007f7fdef7a6e7 /usr/local/MATLAB/MATLAB_Runtime/R2023b/bin/glnxa64/libmwfl.so+00333543

2024-02-09 16:55:26 [ 5] 0x00007f7ef5679549 /usr/local/MATLAB/MATLAB_Runtime/R2023b/bin/glnxa64/matlab_startup_plugins/foundation/platform/pf_matlab_integ/../../../../../../bin/glnxa64/libmwpf_internal.so+00374089

2024-02-09 16:55:26 [ 20] 0x00007f7fc8276caf /usr/local/MATLAB/MATLAB_Runtime/R2023b/bin/glnxa64/matlab_startup_plugins/foundation/platform/pf_matlab_impl/../../../../../../bin/glnxa64/libmwgui.so+00990383 _ZN11gui_objects4font14TeXTextHandler13getTextBoundsEb+00000639

2024-02-09 16:55:26 [ 21] 0x00007f7fc8276e50 /usr/local/MATLAB/MATLAB_Runtime/R2023b/bin/glnxa64/matlab_startup_plugins/foundation/platform/pf_matlab_impl/../../../../../../bin/glnxa64/libmwgui.so+00990800 _ZN11gui_objects4font14TeXTextHandler16getLogicalBoundsEv+00000048

2024-02-09 16:55:26 [ 46] 0x00007f7e9ac904ed /usr/local/MATLAB/MATLAB_Runtime/R2023b/bin/glnxa64/builtins/matlab_graphics_handle_graphics/../../../../bin/glnxa64/libmwhandle_graphics.so+27854061

2024-02-09 16:55:26 [ 47] 0x00007f7fc21d63e3 /usr/local/MATLAB/MATLAB_Runtime/R2023b/bin/glnxa64/matlab_startup_plugins/foundation/platform/pf_matlab_impl/../../../../../../bin/glnxa64/libmwgraphics_util.so+00398307

2024-02-09 16:55:26 [ 48] 0x00007f7fc21bc868 /usr/local/MATLAB/MATLAB_Runtime/R2023b/bin/glnxa64/matlab_startup_plugins/foundation/platform/pf_matlab_impl/../../../../../../bin/glnxa64/libmwgraphics_util.so+00292968 _ZN13graphics_util15callbackHandlerERKN6mlutil10contextmgr5McrIDERKSt8functionIFvvEE+00000136

2024-02-09 16:55:26 [ 49] 0x00007f7e9ac87335 /usr/local/MATLAB/MATLAB_Runtime/R2023b/bin/glnxa64/builtins/matlab_graphics_handle_graphics/../../../../bin/glnxa64/libmwhandle_graphics.so+27816757 _ZN8graphics9primitive6canvas6Canvas14initiateUpdateESt8functionIFvRKNSt7__cxx114listIN7mwboost10shared_ptrIN4mcos12COSEventDataEEESaISA_EEEEE+00000069

2024-02-09 16:55:26 [ 50] 0x00007f7ea0094b93 /usr/local/MATLAB/MATLAB_Runtime/R2023b/bin/glnxa64/builtins/matlab_graphics_web/../../../../bin/glnxa64/libmwhgweb.so+00437139

2024-02-09 16:55:26 [ 51] 0x00007f7ea398477e /usr/local/MATLAB/MATLAB_Runtime/R2023b/bin/glnxa64/builtins/matlab_graphics_hg/../../../../bin/glnxa64/libmwhg.so+05785470

2024-02-09 16:55:26 [ 62] 0x00007f7fc21d63e3 /usr/local/MATLAB/MATLAB_Runtime/R2023b/bin/glnxa64/matlab_startup_plugins/foundation/platform/pf_matlab_impl/../../../../../../bin/glnxa64/libmwgraphics_util.so+00398307

2024-02-09 16:55:26 [ 63] 0x00007f7fc21bc868 /usr/local/MATLAB/MATLAB_Runtime/R2023b/bin/glnxa64/matlab_startup_plugins/foundation/platform/pf_matlab_impl/../../../../../../bin/glnxa64/libmwgraphics_util.so+00292968 _ZN13graphics_util15callbackHandlerERKN6mlutil10contextmgr5McrIDERKSt8functionIFvvEE+00000136

2024-02-09 16:55:26 [ 64] 0x00007f7ea379f4f9 /usr/local/MATLAB/MATLAB_Runtime/R2023b/bin/glnxa64/builtins/matlab_graphics_hg/../../../../bin/glnxa64/libmwhg.so+03798265

2024-02-09 16:55:26 [ 65] 0x00007f7ea395963b /usr/local/MATLAB/MATLAB_Runtime/R2023b/bin/glnxa64/builtins/matlab_graphics_hg/../../../../bin/glnxa64/libmwhg.so+05609019

2024-02-09 16:55:26 [ 66] 0x00007f7ea3830cc5 /usr/local/MATLAB/MATLAB_Runtime/R2023b/bin/glnxa64/builtins/matlab_graphics_hg/../../../../bin/glnxa64/libmwhg.so+04394181

2024-02-09 16:55:26 [ 67] 0x00007f7ea39360b5 /usr/local/MATLAB/MATLAB_Runtime/R2023b/bin/glnxa64/builtins/matlab_graphics_hg/../../../../bin/glnxa64/libmwhg.so+05464245

2024-02-09 16:55:26 [ 68] 0x00007f7fda7c1cef /usr/local/MATLAB/MATLAB_Runtime/R2023b/bin/glnxa64/libmwservices.so+03939567

2024-02-09 16:55:26 [ 69] 0x00007f7fda7c195d /usr/local/MATLAB/MATLAB_Runtime/R2023b/bin/glnxa64/libmwservices.so+03938653 _Z26svWS_CommitDatabaseUpdatesb+00000061

2024-02-09 16:55:26 [ 70] 0x00007f7fda7b8d2e /usr/local/MATLAB/MATLAB_Runtime/R2023b/bin/glnxa64/libmwservices.so+03902766

2024-02-09 16:55:26 [ 71] 0x00007f7fda7bdc61 /usr/local/MATLAB/MATLAB_Runtime/R2023b/bin/glnxa64/libmwservices.so+03923041 _Z25svWS_ProcessPendingEventsiib+00000097

2024-02-09 16:55:26 [ 72] 0x00007f7fafa98d2d /usr/local/MATLAB/MATLAB_Runtime/R2023b/bin/glnxa64/spf/serialisationproviders/parallel/plr_serialisation_provider/../../../../../../bin/glnxa64/libmwdrawnow.so+00433453

2024-02-09 16:55:26 [ 73] 0x00007f7fd82db204 /usr/local/MATLAB/MATLAB_Runtime/R2023b/bin/glnxa64/libmwm_dispatcher.so+00897540

2024-02-09 16:55:26 [ 74] 0x00007f7fd82ddb28 /usr/local/MATLAB/MATLAB_Runtime/R2023b/bin/glnxa64/libmwm_dispatcher.so+00908072

2024-02-09 16:55:26 [ 75] 0x00007f7fd82c1070 /usr/local/MATLAB/MATLAB_Runtime/R2023b/bin/glnxa64/libmwm_dispatcher.so+00790640

2024-02-09 16:55:26 [ 76] 0x00007f7fd82c13be /usr/local/MATLAB/MATLAB_Runtime/R2023b/bin/glnxa64/libmwm_dispatcher.so+00791486 _ZN18Mfh_MATLAB_fn_impl8dispatchEiPSt10unique_ptrI11mxArray_tagN6matrix6detail17mxDestroy_deleterEEiPPS1_+00000030

2024-02-09 16:55:26 [ 77] 0x00007f7fd706eb32 /usr/local/MATLAB/MATLAB_Runtime/R2023b/bin/glnxa64/libmwlxemainservices.so+02550578

2024-02-09 16:55:26 [ 78] 0x00007f7fd706ee34 /usr/local/MATLAB/MATLAB_Runtime/R2023b/bin/glnxa64/libmwlxemainservices.so+02551348

2024-02-09 16:55:26 [ 79] 0x00007f7fd30ca55f /usr/local/MATLAB/MATLAB_Runtime/R2023b/bin/glnxa64/libmwm_lxe.so+11314527

2024-02-09 16:55:26 [103] 0x00007f7fd82c0cdd /usr/local/MATLAB/MATLAB_Runtime/R2023b/bin/glnxa64/libmwm_dispatcher.so+00789725 _ZN18Mfh_MATLAB_fn_impl19dispatch_with_reuseEiPP11mxArray_tagiS2_+00000237

2024-02-09 16:55:26 [122] 0x00007f7fc82571a5 /usr/local/MATLAB/MATLAB_Runtime/R2023b/bin/glnxa64/matlab_startup_plugins/foundation/platform/pf_matlab_impl/../../../../../../bin/glnxa64/libmwgui.so+00860581 _ZNK9MCallback8_executeEP11mxArray_tagS1_iPS1_+00000421

2024-02-09 16:55:26 [127] 0x00007f7ec8817f72 /usr/local/MATLAB/MATLAB_Runtime/R2023b/bin/glnxa64/builtins/matlab_graphics_hg/../../../../bin/glnxa64/libmwhgdatatypes.so+04292466 _ZN16CallbackExecutor17callEventCallbackEN7mwboost10shared_ptrI12CallbackItemEE+00000402

2024-02-09 16:55:26 ** This crash report has been saved to disk as /local/MathWorks/webapps/R2023b/logs/matlab_crash_dump.689079-1 **

2024-02-09 16:55:26 MATLAB is exiting because of fatal error

Answer 1

[C. K.]

I also had the problem with the websockets protocol

I finally solved the problem. In the browser development tools there was an error message saying that the "WebSocket failed with code: 6". This indicates that Web App Server failed to validate the origin of the request. This check was implemented in MATLAB R2021b to prevent cross-site hijacking. One cause of failure is if the protocol from the origin (e.g.: reverse proxy server) does not match the protocol of the Web App Server.

The solution is the following:

If possible, try setting up the Web App Server such that it is on HTTPS mode with SSL enabled. You can do so by following one of the two MATLAB documentation pages below:

Production version: https://www.mathworks.com/help/webappserver/ug/enable-ssl.html

Development version: https://www.mathworks.com/help/compiler/webapps/enabling-https.html

To find out, whether you use the Production oder the Development of MATLAB Web App Server:

If it is the production version, what is the license number? You can find a list of your software licenses by going to your account on the MathWorks site.