[ERROR] mysqld got signal 11 ;

...

Server version: 10.5.1-MariaDB-1:10.5.1+maria~bionic-log

key_buffer_size=134217728

read_buffer_size=2097152

max_used_connections=10

max_threads=102

thread_count=12

It is possible that mysqld could use up to 

key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 760270 K  bytes of memory

Hope that's ok; if not, decrease some variables in the equation.

Thread pointer: 0x7fbd2c000c08

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 = 0x7fbd8c2bdd98 thread_stack 0x3c000

mysqld(my_print_stacktrace+0x2e)[0x564e6a20379e]

Printing to addr2line failed

mysqld(handle_fatal_signal+0x515)[0x564e69c473c5]

/lib/x86_64-linux-gnu/libpthread.so.0(+0x12890)[0x7fbd94280890]

mysqld(my_wc_to_printable_generic+0x3a)[0x564e6a25559a]

mysqld(my_convert_using_func+0x85)[0x564e6a255795]

mysqld(_Z21convert_error_messagePcmPK15charset_info_stPKcmS2_Pj+0x4b)[0x564e69a17ccb]

mysqld(_Z21net_send_error_packetP3THDjPKcS2_+0x96)[0x564e6999ad46]

mysqld(_ZN8Protocol13end_statementEv+0xb9)[0x564e6999af59]

mysqld(_Z16dispatch_command19enum_server_commandP3THDPcjbb+0x5be)[0x564e69a4c74e]

mysqld(_Z10do_commandP3THD+0x138)[0x564e69a4bca8]

mysqld(_Z24do_handle_one_connectionP7CONNECTb+0x3ee)[0x564e69b3f5be]

mysqld(handle_one_connection+0x4b)[0x564e69b3f77b]

/lib/x86_64-linux-gnu/libpthread.so.0(+0x76db)[0x7fbd942756db]

/lib/x86_64-linux-gnu/libc.so.6(clone+0x3f)[0x7fbd9367388f]

Trying to get some variables.

Some pointers may be invalid and cause the dump to abort.

Query (0x7fbd2c0100e0): SELECT

Connection ID (thread ID): 29

Status: NOT_KILLED

Optimizer switch: index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_merge_sort_intersection=off,engine_condition_pushdown=off,index_condition_pushdown=on,derived_merge=on,derived_with_keys=on,firstmatch=on,loosescan=on,materialization=on,in_to_exists=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on,subquery_cache=on,mrr=off,mrr_cost_based=off,mrr_sort_keys=off,outer_join_with_cache=on,semijoin_with_cache=on,join_cache_incremental=on,join_cache_hashed=on,join_cache_bka=on,optimize_join_buffer_size=on,table_elimination=on,extended_keys=on,exists_to_in=on,orderby_uses_equalities=on,condition_pushdown_for_derived=on,split_materialized=on,condition_pushdown_for_subquery=on,rowid_filter=on,condition_pushdown_from_having=on,not_null_range_scan=off

The manual page at http://dev.mysql.com/doc/mysql/en/crashing.html contains

information that should help you find out what is causing the crash.

Writing a core file...

Working directory at /var/lib/mysql

Resource Limits:

Limit                     Soft Limit           Hard Limit           Units     

Max cpu time              unlimited            unlimited            seconds   

Max file size             unlimited            unlimited            bytes     

Max data size             unlimited            unlimited            bytes     

Max stack size            8388608              unlimited            bytes     

Max core file size        0                    unlimited            bytes     

Max resident set          unlimited            unlimited            bytes     

Max processes             unlimited            unlimited            processes 

Max open files            1048576              1048576              files     

Max locked memory         83968000             83968000             bytes     

Max address space         unlimited            unlimited            bytes     

Max file locks            unlimited            unlimited            locks     

Max pending signals       7896                 7896                 signals   

Max msgqueue size         819200               819200               bytes     

Max nice priority         0                    0                    

Max realtime priority     0                    0                    

Max realtime timeout      unlimited            unlimited            us        

Core pattern: core