MATLAB crashing when receiving string markers

[T-Newey]

(Copied from previous LSL4Unity Issue as I accidentally created this there instead of here!)
Hi all,

MATLAB has been crashing when running the example script 'ReceiveStringMarkers'. It opens the stream but doesn't stream any data, crashing instead.
Some things I have tried/checked:

• Receiving normal numerical streams works fine
• Issue occurs regardless of where the stream comes from (i.e., sending string markers from pylsl and LSL4Unity both cause the crash)
• pylsl has no issue receiving markers, and MATLAB can send them without issue
• I have tested on 2 laptops (both running Windows 11, 64-bit, MATLAB R2024b), including one with a fresh version of lsl, mex files, etc. - issue occurs on both

From the crash log generated (see below), it appears to be lsl_pull_sample_str.mexw64 that causes the crash.
As there's no problem with ordinary streams I should be able to work around it for now by sending integers or floats as 'markers' instead. I submitted the crash log and was directed here.
Thanks!

Click to see crash log

MATLAB Log File: C:\Users<username>\AppData\Local\Temp\matlab_crash_dump.38756-1

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MATLAB Log File

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         Access violation detected at 2025-03-23 22:17:23 +0000

---

Configuration:
Crash Decoding : Disabled - No sandbox or build area path
Crash Mode : continue (default)
Default Encoding : UTF-8
Deployed : false
Graphics Driver : Uninitialized hardware
Graphics card 1 : NVIDIA ( 0x10de ) NVIDIA GeForce RTX 3050 Ti Laptop GPU Version 32.0.15.5612 (2024-6-25)
Graphics card 2 : Intel Corporation ( 0x8086 ) Intel(R) Iris(R) Xe Graphics Version 31.0.101.5186 (2024-1-18)
Interpreter 0 : Executing request: 4D61746C6162526571756573742E637070
Java Version : Java 1.8.0_202-b08 with Oracle Corporation Java HotSpot(TM) 64-Bit Server VM mixed mode
MATLAB Architecture : win64
MATLAB Entitlement ID : 5013865
MATLAB Root : C:\Program Files\MATLAB\R2024b
MATLAB Version : 24.2.0.2806996 (R2024b) Update 3
OpenGL : hardware
Operating System : Microsoft Windows 11 Enterprise
Process ID : 38756
Processor ID : x86 Family 6 Model 154 Stepping 3, GenuineIntel
Session Key : d6df255a-6268-4854-b789-343e7b4fb14b
Window System : Version 10.0 (Build 22631)

Fault Count: 1

Abnormal termination:
Access violation

Current Thread: 'MCR 0 interpreter thread' id 40548

Register State (from fault):
RAX = 000001f8dc5e3620 RBX = 0065006e006f0070
RCX = 0000000000005ec0 RDX = 000001f8dc5e94f0
RSP = 0000009a683e7940 RBP = 000001f8dc5e94e0
RSI = 000001f8dc5e94f0 RDI = 0000000000000000

R8 = 00000000a07d3830 R9 = 0000000000000000
R10 = 0000000000000003 R11 = 0000009a683e7950
R12 = 0000000000000000 R13 = 000001f8f7c80000
R14 = 000001f8eaf63c70 R15 = 0000000000000000

RIP = 00007ff8572dcfc1 EFL = 00010202

CS = 0033 FS = 0053 GS = 002b

Stack Trace (from fault):
[ 0] 0x00007ff8572dcfc1 C:\Windows\SYSTEM32\ntdll.dll+00708545 memcpy+00024705
[ 1] 0x00007ff85726b001 C:\Windows\SYSTEM32\ntdll.dll+00241665 RtlFreeHeap+00000081
[ 2] 0x00007ff85586cadc C:\Windows\System32\msvcrt.dll+00117468 free+00000028
[ 3] 0x000000006bc41566 C:\Users<username>\Documents\MATLAB\liblsl-Matlab\bin\lsl_pull_sample_str.mexw64+00005478 mexFunction+00000438
[ 4] 0x00007fff57876149 C:\Program Files\MATLAB\R2024b\bin\win64\libmex.dll+00680265 mexfile::Inspector::needs_upgrade+00023801
[ 5] 0x00007fff57879152 C:\Program Files\MATLAB\R2024b\bin\win64\libmex.dll+00692562 MexRetrieveVersion+00009074
[ 6] 0x00007fff578792c7 C:\Program Files\MATLAB\R2024b\bin\win64\libmex.dll+00692935 MexRetrieveVersion+00009447
[ 7] 0x00007fff578794b8 C:\Program Files\MATLAB\R2024b\bin\win64\libmex.dll+00693432 MexRetrieveVersion+00009944
[ 8] 0x00007fff5785b6b8 C:\Program Files\MATLAB\R2024b\bin\win64\libmex.dll+00571064 mexUnlock+00018024
[ 9] 0x00007fff590e2a48 C:\Program Files\MATLAB\R2024b\bin\win64\m_dispatcher.dll+01190472 Mfh_file::dispatch_file_common+00000152
[ 10] 0x00007fff590e1909 C:\Program Files\MATLAB\R2024b\bin\win64\m_dispatcher.dll+01186057 Mfh_error::lookup+00012425
[ 11] 0x00007fff590e299d C:\Program Files\MATLAB\R2024b\bin\win64\m_dispatcher.dll+01190301 Mfh_file::dispatch+00000045
[ 12] 0x00007fff56de753d C:\Program Files\MATLAB\R2024b\bin\win64\libmwlxemainservices.dll+00423229 coretypes::array::Array<MathWorks::String::detail::StringArrayVariant,MathWorks::String::detail::StringArrayPolicy,coretypes::array::ArrayTypeListMathWorks::String::detail::StringArrayVariant >::resize+00351613
[ 13] 0x00007fff56df639e C:\Program Files\MATLAB\R2024b\bin\win64\libmwlxemainservices.dll+00484254 coretypes::array::Array<MathWorks::String::detail::StringArrayVariant,MathWorks::String::detail::StringArrayPolicy,coretypes::array::ArrayTypeListMathWorks::String::detail::StringArrayVariant >::resize+00412638
[ 14] 0x00007fff49c70fe6 C:\Program Files\MATLAB\R2024b\bin\win64\m_lxe.dll+06361062 MathWorks::lxe::ReadOnlyXvaluePtr::operator=+00006966
[ 15] 0x00007fff49c72e2b C:\Program Files\MATLAB\R2024b\bin\win64\m_lxe.dll+06368811 MathWorks::lxe::ReadOnlyXvaluePtr::operator=+00014715
[ 16] 0x00007fff49b9e7e8 C:\Program Files\MATLAB\R2024b\bin\win64\m_lxe.dll+05498856 MathWorks::lxe::XvalueFactory::XvalueDeleter::XvalueDeleter+00225192
[ 17] 0x00007fff49bbdbc9 C:\Program Files\MATLAB\R2024b\bin\win64\m_lxe.dll+05626825 MathWorks::lxe::XvalueFactory::XvalueDeleter::XvalueDeleter+00353161
[ 18] 0x00007fff49955f76 C:\Program Files\MATLAB\R2024b\bin\win64\m_lxe.dll+03104630 MathWorks::lxe::LXEConstants::IsIfElse+00547062
[ 19] 0x00007fff4995a162 C:\Program Files\MATLAB\R2024b\bin\win64\m_lxe.dll+03121506 MathWorks::lxe::LXEConstants::IsY+00012018
[ 20] 0x00007fff49957983 C:\Program Files\MATLAB\R2024b\bin\win64\m_lxe.dll+03111299 MathWorks::lxe::LXEConstants::IsY+00001811
[ 21] 0x00007fff4995b265 C:\Program Files\MATLAB\R2024b\bin\win64\m_lxe.dll+03125861 MathWorks::lxe::LXEConstants::IsY+00016373
[ 22] 0x00007fff4995b513 C:\Program Files\MATLAB\R2024b\bin\win64\m_lxe.dll+03126547 MathWorks::lxe::LXEConstants::IsY+00017059
[ 23] 0x00007fff4995ae7e C:\Program Files\MATLAB\R2024b\bin\win64\m_lxe.dll+03124862 MathWorks::lxe::LXEConstants::IsY+00015374
[ 24] 0x00007fff499570c6 C:\Program Files\MATLAB\R2024b\bin\win64\m_lxe.dll+03109062 MathWorks::lxe::LxeTypes::GetTypeXvalueOf+00000262
[ 25] 0x00007fff49a53e67 C:\Program Files\MATLAB\R2024b\bin\win64\m_lxe.dll+04144743 MathWorks::lxe::SetEngineImplUnlinkFlagForAllCallsOnStack+00049303
[ 26] 0x00007fff49a579e5 C:\Program Files\MATLAB\R2024b\bin\win64\m_lxe.dll+04159973 MathWorks::lxe::SetEngineImplUnlinkFlagForAllCallsOnStack+00064533
[ 27] 0x00007fff56ee9816 C:\Program Files\MATLAB\R2024b\bin\win64\libmwlxemainservices.dll+01480726 FeatureTestObservableWorkspace+00212358
[ 28] 0x00007fff56ddf783 C:\Program Files\MATLAB\R2024b\bin\win64\libmwlxemainservices.dll+00391043 coretypes::array::Array<MathWorks::String::detail::StringArrayVariant,MathWorks::String::detail::StringArrayPolicy,coretypes::array::ArrayTypeListMathWorks::String::detail::StringArrayVariant >::resize+00319427
[ 29] 0x00007fff56ddedd3 C:\Program Files\MATLAB\R2024b\bin\win64\libmwlxemainservices.dll+00388563 coretypes::array::Array<MathWorks::String::detail::StringArrayVariant,MathWorks::String::detail::StringArrayPolicy,coretypes::array::ArrayTypeListMathWorks::String::detail::StringArrayVariant >::resize+00316947
[ 30] 0x00007fff56de19e2 C:\Program Files\MATLAB\R2024b\bin\win64\libmwlxemainservices.dll+00399842 coretypes::array::Array<MathWorks::String::detail::StringArrayVariant,MathWorks::String::detail::StringArrayPolicy,coretypes::array::ArrayTypeListMathWorks::String::detail::StringArrayVariant >::resize+00328226
[ 31] 0x00007fff590e2a48 C:\Program Files\MATLAB\R2024b\bin\win64\m_dispatcher.dll+01190472 Mfh_file::dispatch_file_common+00000152
[ 32] 0x00007fff590e1909 C:\Program Files\MATLAB\R2024b\bin\win64\m_dispatcher.dll+01186057 Mfh_error::lookup+00012425
[ 33] 0x00007fff590e299d C:\Program Files\MATLAB\R2024b\bin\win64\m_dispatcher.dll+01190301 Mfh_file::dispatch+00000045
[ 34] 0x00007fff56de753d C:\Program Files\MATLAB\R2024b\bin\win64\libmwlxemainservices.dll+00423229 coretypes::array::Array<MathWorks::String::detail::StringArrayVariant,MathWorks::String::detail::StringArrayPolicy,coretypes::array::ArrayTypeListMathWorks::String::detail::StringArrayVariant >::resize+00351613
[ 35] 0x00007fff56df639e C:\Program Files\MATLAB\R2024b\bin\win64\libmwlxemainservices.dll+00484254 coretypes::array::Array<MathWorks::String::detail::StringArrayVariant,MathWorks::String::detail::StringArrayPolicy,coretypes::array::ArrayTypeListMathWorks::String::detail::StringArrayVariant >::resize+00412638
[ 36] 0x00007fff49c70fe6 C:\Program Files\MATLAB\R2024b\bin\win64\m_lxe.dll+06361062 MathWorks::lxe::ReadOnlyXvaluePtr::operator=+00006966
[ 37] 0x00007fff49c72675 C:\Program Files\MATLAB\R2024b\bin\win64\m_lxe.dll+06366837 MathWorks::lxe::ReadOnlyXvaluePtr::operator=+00012741
[ 38] 0x00007fff49b9e7e8 C:\Program Files\MATLAB\R2024b\bin\win64\m_lxe.dll+05498856 MathWorks::lxe::XvalueFactory::XvalueDeleter::XvalueDeleter+00225192
[ 39] 0x00007fff49bbd7b9 C:\Program Files\MATLAB\R2024b\bin\win64\m_lxe.dll+05625785 MathWorks::lxe::XvalueFactory::XvalueDeleter::XvalueDeleter+00352121
[ 40] 0x00007fff49955f76 C:\Program Files\MATLAB\R2024b\bin\win64\m_lxe.dll+03104630 MathWorks::lxe::LXEConstants::IsIfElse+00547062
[ 41] 0x00007fff4995a162 C:\Program Files\MATLAB\R2024b\bin\win64\m_lxe.dll+03121506 MathWorks::lxe::LXEConstants::IsY+00012018
[ 42] 0x00007fff49957983 C:\Program Files\MATLAB\R2024b\bin\win64\m_lxe.dll+03111299 MathWorks::lxe::LXEConstants::IsY+00001811
[ 43] 0x00007fff4995b265 C:\Program Files\MATLAB\R2024b\bin\win64\m_lxe.dll+03125861 MathWorks::lxe::LXEConstants::IsY+00016373
[ 44] 0x00007fff4995b513 C:\Program Files\MATLAB\R2024b\bin\win64\m_lxe.dll+03126547 MathWorks::lxe::LXEConstants::IsY+00017059
[ 45] 0x00007fff4995ae7e C:\Program Files\MATLAB\R2024b\bin\win64\m_lxe.dll+03124862 MathWorks::lxe::LXEConstants::IsY+00015374
[ 46] 0x00007fff499570c6 C:\Program Files\MATLAB\R2024b\bin\win64\m_lxe.dll+03109062 MathWorks::lxe::LxeTypes::GetTypeXvalueOf+00000262
[ 47] 0x00007fff49a53e67 C:\Program Files\MATLAB\R2024b\bin\win64\m_lxe.dll+04144743 MathWorks::lxe::SetEngineImplUnlinkFlagForAllCallsOnStack+00049303
[ 48] 0x00007fff49a579e5 C:\Program Files\MATLAB\R2024b\bin\win64\m_lxe.dll+04159973 MathWorks::lxe::SetEngineImplUnlinkFlagForAllCallsOnStack+00064533
[ 49] 0x00007fff56ee9816 C:\Program Files\MATLAB\R2024b\bin\win64\libmwlxemainservices.dll+01480726 FeatureTestObservableWorkspace+00212358
[ 50] 0x00007fff56e2b0f6 C:\Program Files\MATLAB\R2024b\bin\win64\libmwlxemainservices.dll+00700662 mwboost::archive::detail::pointer_oserializermwboost::archive::xml_oarchive,MathWorks::lxe::PreLineExecutionEvent::save_object_ptr+00074918
[ 51] 0x00007fff56e2cbf4 C:\Program Files\MATLAB\R2024b\bin\win64\libmwlxemainservices.dll+00707572 mwboost::archive::detail::pointer_oserializermwboost::archive::xml_oarchive,MathWorks::lxe::PreLineExecutionEvent::save_object_ptr+00081828
[ 52] 0x00007fff56eacb77 C:\Program Files\MATLAB\R2024b\bin\win64\libmwlxemainservices.dll+01231735 mwboost::archive::detail::oserializermwboost::archive::text_oarchive,MathWorks::MatlabComponents::ComponentIdentifier::save_object_data+00327655
[ 53] 0x00007fff56eae977 C:\Program Files\MATLAB\R2024b\bin\win64\libmwlxemainservices.dll+01239415 mwboost::archive::detail::oserializermwboost::archive::text_oarchive,MathWorks::MatlabComponents::ComponentIdentifier::save_object_data+00335335
[ 54] 0x00007fff56eadc60 C:\Program Files\MATLAB\R2024b\bin\win64\libmwlxemainservices.dll+01236064 mwboost::archive::detail::oserializermwboost::archive::text_oarchive,MathWorks::MatlabComponents::ComponentIdentifier::save_object_data+00331984
[ 55] 0x00007fff57949ca9 C:\Program Files\MATLAB\R2024b\bin\win64\libmwbridge.dll+00302249 mnGetPrompt+00013993
[ 56] 0x00007fff5978b676 C:\Program Files\MATLAB\R2024b\bin\win64\iqm.dll+00505462 iqm::Iqm::instance+00002358
[ 57] 0x00007fff597e4ed2 C:\Program Files\MATLAB\R2024b\bin\win64\iqm.dll+00872146 iqm::UserEvalPlugin::execute+00001314
[ 58] 0x00007fff597b229f C:\Program Files\MATLAB\R2024b\bin\win64\iqm.dll+00664223 iqm::Iqm::setupIqmFcnPtrs+00110911
[ 59] 0x00007fff597be32d C:\Program Files\MATLAB\R2024b\bin\win64\iqm.dll+00713517 iqm::Iqm::setupIqmFcnPtrs+00160205
[ 60] 0x00007fff5977ea0f C:\Program Files\MATLAB\R2024b\bin\win64\iqm.dll+00453135 iqm::Iqm::create+00010543
[ 61] 0x00007fff57919546 C:\Program Files\MATLAB\R2024b\bin\win64\libmwbridge.dll+00103750 ioReadLine+00000406
[ 62] 0x00007fff57919375 C:\Program Files\MATLAB\R2024b\bin\win64\libmwbridge.dll+00103285 ioReadLine+00000165
[ 63] 0x00007fff5794a070 C:\Program Files\MATLAB\R2024b\bin\win64\libmwbridge.dll+00303216 mnGetCommandLineBuffer+00000288
[ 64] 0x00007fff5794a517 C:\Program Files\MATLAB\R2024b\bin\win64\libmwbridge.dll+00304407 mnParser+00000487
[ 65] 0x00007fff595fd19f C:\Program Files\MATLAB\R2024b\bin\win64\mcr.dll+00446879 mcr_initialize_main+00016975
[ 66] 0x00007fff595a91de C:\Program Files\MATLAB\R2024b\bin\win64\mcr.dll+00102878 mcrFunctionSignature::set_signature+00080062
[ 67] 0x00007fff595c63c2 C:\Program Files\MATLAB\R2024b\bin\win64\mcr.dll+00222146 mwboost::archive::codecvt_null<wchar_t>::`default constructor closure'+00017266
[ 68] 0x00007fff597dfe2a C:\Program Files\MATLAB\R2024b\bin\win64\iqm.dll+00851498 iqm::PackagedTaskPlugin::execute+00000074
[ 69] 0x00007fff597b229f C:\Program Files\MATLAB\R2024b\bin\win64\iqm.dll+00664223 iqm::Iqm::setupIqmFcnPtrs+00110911
[ 70] 0x00007fff5977f32a C:\Program Files\MATLAB\R2024b\bin\win64\iqm.dll+00455466 iqm::Iqm::create+00012874
[ 71] 0x00007fff5977f811 C:\Program Files\MATLAB\R2024b\bin\win64\iqm.dll+00456721 iqm::Iqm::create+00014129
[ 72] 0x00007fff5977ec9d C:\Program Files\MATLAB\R2024b\bin\win64\iqm.dll+00453789 iqm::Iqm::create+00011197
[ 73] 0x00007fff595e1b7c C:\Program Files\MATLAB\R2024b\bin\win64\mcr.dll+00334716 mcrInstantiationError::operator=+00010652
[ 74] 0x00007fff595e263f C:\Program Files\MATLAB\R2024b\bin\win64\mcr.dll+00337471 mcrInstantiationError::operator=+00013407
[ 75] 0x00007fff595dfc41 C:\Program Files\MATLAB\R2024b\bin\win64\mcr.dll+00326721 mcrInstantiationError::operator=+00002657
[ 76] 0x00007ff8347f8fba C:\Program Files\MATLAB\R2024b\bin\win64\mwboost_thread-vc143-mt-x64-1_81.dll+00036794 mwboost::detail::win32::handle_manager::swap+00000650
[ 77] 0x00007ff854459333 C:\Windows\System32\ucrtbase.dll+00168755 recalloc+00000163
[ 78] 0x00007ff8550a259d C:\Windows\System32\KERNEL32.DLL+00075165 BaseThreadInitThunk+00000029
[ 79] 0x00007ff85728af38 C:\Windows\SYSTEM32\ntdll.dll+00372536 RtlUserThreadStart+00000040

This error was detected while a MEX-file was running. If the MEX-file
is not an official MathWorks function, please examine its source code
for errors. Please consult the External Interfaces Guide for information
on debugging MEX-files.