Update from 2018.4.32f1 to 2021.3.14f1 crashes SIGSEGV UI::PrepareOutput

Unity Engine
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After updating Unity from 2018.4.32f1 to 2021.3.14f1, we encountered a new type of crashes. Later, we updated to 2021.3.21f1, but it did not resolve them. There are multiple variations of stack trace but they all have this part in common:

Stack trace variant 1:

null pointer dereference: SIGSEGV  0x0000000000000004
#00 pc 0x5410f8 libunity.so (dynamic_array<UI::smile:epthSortEntry, 0ul>::grow()) (BuildId: e40fbfaec3bd5f5bdc8dd091f6c2a801b6fa202e)
#01 pc 0x53e93c libunity.so (UI::PrepareOutput(GfxDevice&, UI::Batches&, unsigned int, unsigned int, UI::AdditionalCanvasShaderChannels, unsigned char)) (BuildId: e40fbfaec3bd5f5bdc8dd091f6c2a801b6fa202e)
#02 pc 0x53eadc libunity.so (UI::PrepareOutput(GfxDevice&, UI::Batches&, unsigned int, unsigned int, UI::AdditionalCanvasShaderChannels, unsigned char)) (BuildId: e40fbfaec3bd5f5bdc8dd091f6c2a801b6fa202e)
#03 pc 0x20d834 libunity.so (JobQueue::Exec(JobInfo*, long long, int, bool)) (BuildId: e40fbfaec3bd5f5bdc8dd091f6c2a801b6fa202e)
#04 pc 0x20daec libunity.so (JobQueue::Steal(JobGroup*, JobInfo*, long long, int, bool, bool)) (BuildId: e40fbfaec3bd5f5bdc8dd091f6c2a801b6fa202e)
#05 pc 0x20dc58 libunity.so (JobQueue::ExecuteJobFromQueue(bool, bool&)) (BuildId: e40fbfaec3bd5f5bdc8dd091f6c2a801b6fa202e)
#06 pc 0x20de98 libunity.so (JobQueue::ProcessJobs(JobQueue::ThreadInfo*, void*)) (BuildId: e40fbfaec3bd5f5bdc8dd091f6c2a801b6fa202e)
#07 pc 0x1149d44 libunity.so (__emutls_register_common [emutls.c:249]) (BuildId: e40fbfaec3bd5f5bdc8dd091f6c2a801b6fa202e)
#08 pc 0x11a703c libunity.so (__emutls_register_common [emutls.c:249]) (BuildId: e40fbfaec3bd5f5bdc8dd091f6c2a801b6fa202e)
#09 pc 0x20d1c8 libunity.so (JobQueue::WorkLoop(void*)) (BuildId: e40fbfaec3bd5f5bdc8dd091f6c2a801b6fa202e)
#10 pc 0x2b4d84 libunity.so (Thread::RunThreadWrapper(void*)) (BuildId: e40fbfaec3bd5f5bdc8dd091f6c2a801b6fa202e)
#11 pc 0xe2630a libunity.so (__emutls_register_common [emutls.c:249]) (BuildId: e40fbfaec3bd5f5bdc8dd091f6c2a801b6fa202e)
#12 pc 0x11aed9c libunity.so (__emutls_register_common [emutls.c:249]) (BuildId: e40fbfaec3bd5f5bdc8dd091f6c2a801b6fa202e)
#13 pc 0x530ffc libc.so (BuildId: 544bc6c8e3556e98efbc4406b97f6a3e)
#14 pc 0xc37f4 libc.so (BuildId: 544bc6c8e3556e98efbc4406b97f6a3e)
#15 pc 0x5d0c4 libc.so (BuildId: 544bc6c8e3556e98efbc4406b97f6a3e)
#16 pc 0xc3720 libc.so (BuildId: 544bc6c8e3556e98efbc4406b97f6a3e)
#17 pc 0x2b4ca8 libunity.so (CurrentThreadIsMainThread()) (BuildId: e40fbfaec3bd5f5bdc8dd091f6c2a801b6fa202e)

Stack trace variant 2:

null pointer dereference: SIGSEGV  0x0000000000000000
#00 pc 0x53fba8 libunity.so (UI::PrepareOutput(GfxDevice&, UI::Batches&, unsigned int, unsigned int, UI::AdditionalCanvasShaderChannels, unsigned char)) (BuildId: e40fbfaec3bd5f5bdc8dd091f6c2a801b6fa202e)
#01 pc 0x20d824 libunity.so (JobQueue::Exec(JobInfo*, long long, int, bool)) (BuildId: e40fbfaec3bd5f5bdc8dd091f6c2a801b6fa202e)
#02 pc 0x20daec libunity.so (JobQueue::Steal(JobGroup*, JobInfo*, long long, int, bool, bool)) (BuildId: e40fbfaec3bd5f5bdc8dd091f6c2a801b6fa202e)
#03 pc 0x20dc58 libunity.so (JobQueue::ExecuteJobFromQueue(bool, bool&)) (BuildId: e40fbfaec3bd5f5bdc8dd091f6c2a801b6fa202e)
#04 pc 0x20de98 libunity.so (JobQueue::ProcessJobs(JobQueue::ThreadInfo*, void*)) (BuildId: e40fbfaec3bd5f5bdc8dd091f6c2a801b6fa202e)
#05 pc 0x1149d44 libunity.so (__emutls_register_common [emutls.c:249]) (BuildId: e40fbfaec3bd5f5bdc8dd091f6c2a801b6fa202e)
#06 pc 0x11a703c libunity.so (__emutls_register_common [emutls.c:249]) (BuildId: e40fbfaec3bd5f5bdc8dd091f6c2a801b6fa202e)
#07 pc 0x20d1c8 libunity.so (JobQueue::WorkLoop(void*)) (BuildId: e40fbfaec3bd5f5bdc8dd091f6c2a801b6fa202e)
#08 pc 0x2b4d84 libunity.so (Thread::RunThreadWrapper(void*)) (BuildId: e40fbfaec3bd5f5bdc8dd091f6c2a801b6fa202e)
#09 pc 0xe2630a libunity.so (__emutls_register_common [emutls.c:249]) (BuildId: e40fbfaec3bd5f5bdc8dd091f6c2a801b6fa202e)
#10 pc 0x11aed9c libunity.so (__emutls_register_common [emutls.c:249]) (BuildId: e40fbfaec3bd5f5bdc8dd091f6c2a801b6fa202e)
#11 pc 0x527ffc libc.so (BuildId: 7841d31efc11481579e4cb75ccbcdb4f)
#12 pc 0xbe888 libc.so (BuildId: 7841d31efc11481579e4cb75ccbcdb4f)
#13 pc 0x5b370 libc.so (BuildId: 7841d31efc11481579e4cb75ccbcdb4f)
#14 pc 0xbe7b4 libc.so (BuildId: 7841d31efc11481579e4cb75ccbcdb4f)
#15 pc 0x2b4ca8 libunity.so (CurrentThreadIsMainThread()) (BuildId: e40fbfaec3bd5f5bdc8dd091f6c2a801b6fa202e)

These are some of the most common crashes overall, but on the Samsung Galaxy A53 5G, they result in a crash rate of 7%. We had no luck trying to reproduce it though.

Do these stack traces make sense? I rebuilt symbols on the same machine and Unity version and got the same results using the Android Logcat Stacktrace Utility. It’s confusing that I can’t find any information about a problem that affects so many players.

Is this a known Unity problem? Perhaps even one that has already been resolved (2021 is old). If so, which version should we try?

2

The first error looks like it might be an a memory problem. It seems to be trying to enlarge an array. Maybe try reducing memory use if that’s possible.

3

This might be the case. The average RAM free value is lower for these crashes compared to non-fatal errors. This applies to other crashes as well. We’ll try to optimize memory usage and reporting. Thank you!