210914 0:06:06 [ERROR] mysqld got signal 11 ; 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: 10.6.4-MariaDB-1:10.6.4+maria~focal-log key_buffer_size=134217728 read_buffer_size=131072 max_used_connections=13 max_threads=252 thread_count=13 It is possible that mysqld could use up to key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 685957 K bytes of memory Hope that's ok; if not, decrease some variables in the equation. Thread pointer: 0x7fa82c00b518 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 = 0x7fa879c4bd98 thread_stack 0x49000 Printing to addr2line failed mysqld(my_print_stacktrace+0x32)[0x5630b6d21f12] mysqld(handle_fatal_signal+0x485)[0x5630b67dc2b5] /lib/x86_64-linux-gnu/libpthread.so.0(+0x153c0)[0x7fa9167523c0] [0x7fa82c010065] Trying to get some variables. Some pointers may be invalid and cause the dump to abort. Query (0x7fa82c01bf80): select * from u_users where id = '172396' limit 1 Connection ID (thread ID): 27 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_equalit ies=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 https://mariadb.com/kb/en/how-to-produce-a-full-stack-trace-for-mysqld/ 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 64017 64017 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