Hosts in this cluster are occasionally crashing, with this message each time.

Here's what got written to our mysql-error.log ...

mysqld: /home/buildbot/buildbot/padding_for_CPACK_RPM_BUILD_SOURCE_DIRS_PREFIX/mariadb-10.4.11/wsrep-lib/src/client_state.cpp:121: int wsrep::client_state::before_command(): Assertion `server_state_.rollback_mode() == wsrep::server_state::rm_async' failed.
200211 21:41:48 [ERROR] mysqld got signal 6 ;
This could be because you hit a bug. It is also possible that this binary
or one of the libraries it was linked against is corrupt, improperly built,
or misconfigured. This error can also be caused by malfunctioning hardware.

To report this bug, see https://mariadb.com/kb/en/reporting-bugs

We will try our best to scrape up some info that will hopefully help
diagnose the problem, but since we have already crashed,
something is definitely wrong and this may fail.

Server version: 10.4.11-MariaDB
key_buffer_size=33554432
read_buffer_size=131072
max_used_connections=278
max_threads=65541
thread_count=238
It is possible that mysqld could use up to
key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 142750971 K bytes of memory
Hope that's ok; if not, decrease some variables in the equation.

Thread pointer: 0x7f113c0c73b8
Attempting backtrace. You can use the following information to find out
where mysqld died. If you see no messages after this, something went
terribly wrong...
stack_bottom = 0x7f12fb93ec98 thread_stack 0x49000

• • • stack smashing detected ***: /usr/sbin/mysqld terminated
      ======= Backtrace: =========
      /lib64/libc.so.6(__fortify_fail+0x37)[0x7f1513812877]
      /lib64/libc.so.6(__fortify_fail+0x0)[0x7f1513812840]
      /usr/sbin/mysqld(+0xe3b93c)[0x562eb83c893c]
      /usr/sbin/mysqld(my_print_stacktrace+0x1c6)[0x562eb83b17a6]
      /usr/sbin/mysqld(handle_fatal_signal+0x4b7)[0x562eb7e80557]
      /lib64/libpthread.so.0(+0x3ff8c0f7e0)[0x7f15150e87e0]
      /lib64/libc.so.6(gsignal+0x35)[0x7f15137424f5]
      /lib64/libc.so.6(abort+0x175)[0x7f1513743cd5]
      /lib64/libc.so.6(+0x3ff882b66e)[0x7f151373b66e]
      /lib64/libc.so.6(__assert_perror_fail+0x0)[0x7f151373b730]
      /usr/sbin/mysqld(_ZN5wsrep12client_state14before_commandEv+0x320)[0x562eb8431150]
      /usr/sbin/mysqld(_Z10do_commandP3THD+0x1a4)[0x562eb7c9d1d4]
      /usr/sbin/mysqld(_Z11tp_callbackP13TP_connection+0x58)[0x562eb7e55568]
      /usr/sbin/mysqld(+0xa56dd8)[0x562eb7fe3dd8]
      /usr/sbin/mysqld(+0xa856fd)[0x562eb80126fd]
      /lib64/libpthread.so.0(+0x3ff8c07aa1)[0x7f15150e0aa1]
      /lib64/libc.so.6(clone+0x6d)[0x7f15137f8c4d]