Asterisk restarting

Hello,
we have FreePBX 15.0.17.9 with Asterisk 16.11.1.
Users have problems with cutting calls.
In asterisk full log we can see:

Asterisk 16.11.1 built by mockbuild @ jenkins7 on a x86_64 running Linux on 2020-07-20 19:57:13 UTC
[2021-12-27 15:02:12] VERBOSE[19752] message.c: Message handler ‘dialplan’ registered.
[2021-12-27 15:02:12] VERBOSE[19752] pbx_functions.c: Registered custom function ‘MESSAGE’
[2021-12-27 15:02:12] VERBOSE[19752] pbx_functions.c: Registered custom function ‘MESSAGE_DATA’
[2021-12-27 15:02:12] VERBOSE[19752] pbx_app.c: Registered application ‘MessageSend’
[2021-12-27 15:02:12] VERBOSE[19752] manager.c: Manager registered action MessageSend
[2021-12-27 15:02:12] VERBOSE[19752] channel.c: Registered channel type ‘Surrogate’ (Surrogate channel used to pull channel from an application)
[2021-12-27 15:02:12] VERBOSE[19752] manager.c: Manager registered action BridgeTechnologyList
[2021-12-27 15:02:12] VERBOSE[19752] manager.c: Manager registered action BridgeTechnologySuspend
[2021-12-27 15:02:12] VERBOSE[19752] manager.c: Manager registered action BridgeTechnologyUnsuspend
[2021-12-27 15:02:12] VERBOSE[19752] dns_core.c: Registered DNS resolver ‘system’ with priority ‘2147483647’
[2021-12-27 15:02:12] VERBOSE[19752] pbx.c: Asterisk PBX Core Initializing

It happens randomly, maybe 0 - 3 times a day.
Seems that Asterisk is restarting?
How can we understand why its restarting?

By looking at the log before the monitoring process (possibly safe_asterisk) re-launched the crashed asterisk process, and by analysing the core dump, as described in Getting a Backtrace - Asterisk Project - Asterisk Project Wiki

Your log shows part of an apparently normal start up.

The log may not show any evidence of the actual crash, but it may reveal that you were doing something sufficiently unusual that most users would not encounter the problem, and doing so just before the crash.

It would also be advisable to upgrade to version 16.23.1, as there will have been many bugs fixed since your version.

More FreePBX specific FreePBX information can be found at:

https://wiki.freepbx.org/display/SUP/Providing+Great+Debug#ProvidingGreatDebug-Backtraces(Segfaults/CoreDumps/AsteriskCrashing)

Very often there will be a hint in /var/log/{messages,syslog} at exctly the same times as asterisk crashed as to why asterisk actually crashed.

Thanks for your reply.

Have not found any suspecious warnings nor errors before crash. Everything seems to be ok. Core dump was created automatically just in time when asterisk crashed and restarted. Opened core dump with gdb program and found this:
Program terminated with signal SIGSEGV, Segmentation fault.
#0 0x00007fd92465c45b in ?? ()
What is the reason for this? Where to move further?
At this stage we can not update system cause many processes are dependant on the FreePBX and we dont want to do worse.

The code tried to access memory that wasn’t allocated to it. It looks like that might have been preceded by a jump to an invalid address.

Basically, there are no easy answers to crashes. To the extent that there is an easy answer, just upgrading to the latest version will solve the problem, as the only really easy answers are for those cases that have already been fixed.

If it still breaks on the latest version, you will need to think more carefully about what it might have been trying to do. It is likely to be doing something that few people do, as crashes that affect lots of people tend to get found quickly.

What is the latest version in my case? 16.23.1? What is the procedure to update to this version? Where can I read about this? Is it dangerous, cause in our FreePBX we have integration with CRM?

The latest version in the Asterisk 16 series is 16.23.0. There is no 16.23.1.