WordPress update -> Assertion failure

When updating WordPress, get the following error. Pretty serious issue for those who keep their server updated (which must be everyone) and want to keep WordPress updated (which must be everyone as well).

Full error log:
2020-02-29 15:39:35 0x7ffbb8f66700 InnoDB: Assertion failure in file /home/buildbot/buildbot/padding_for_CPACK_RPM_BUILD_SOURCE_DIRS_PREFIX/mariadb-10.4.11/storage/innobase/data/data0type.cc line 67
InnoDB: Failing assertion: !(prefix_len % mbmaxlen)
InnoDB: We intentionally generate a memory trap.
InnoDB: Submit a detailed bug report to https://jira.mariadb.org/
InnoDB: If you get repeated assertion failures or crashes, even
InnoDB: immediately after the mysqld startup, there may be
InnoDB: corruption in the InnoDB tablespace. Please refer to
InnoDB: https://mariadb.com/kb/en/library/innodb-recovery-modes/
InnoDB: about forcing recovery.
200229 15:39:35 [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=134217728
read_buffer_size=131072
max_used_connections=10
max_threads=153
thread_count=16
It is possible that mysqld could use up to
key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 467743 K bytes of memory
Hope that's ok; if not, decrease some variables in the equation.

Thread pointer: 0x7ffb50000a88
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 = 0x7ffbb8f65cf0 thread_stack 0x49000
/usr/sbin/mysqld(my_print_stacktrace+0x2e)[0x557eed68cebe]
/usr/sbin/mysqld(handle_fatal_signal+0x30f)[0x557eed1254cf]
sigaction.c:0(__restore_rt)[0x7ffbc1ce35f0]
:0(__GI_raise)[0x7ffbbffb4337]
:0(__GI_abort)[0x7ffbbffb5a28]
/usr/sbin/mysqld(+0x5a2820)[0x557eece21820]
/usr/sbin/mysqld(+0xbfc29c)[0x557eed47b29c]
/usr/sbin/mysqld(+0xb0a070)[0x557eed389070]
/usr/sbin/mysqld(+0xb0f9de)[0x557eed38e9de]
/usr/sbin/mysqld(+0xb12a07)[0x557eed391a07]
/usr/sbin/mysqld(+0xa6a2de)[0x557eed2e92de]
/usr/sbin/mysqld(_Z17mysql_alter_tableP3THDPK25st_mysql_const_lex_stringS3_P14HA_CREATE_INFOP10TABLE_LISTP10Alter_infojP8st_orderb+0x3228)[0x557eecfb0ed8]
/usr/sbin/mysqld(_ZN19Sql_cmd_alter_table7executeEP3THD+0x3ff)[0x557eed0068ef]
/usr/sbin/mysqld(_Z21mysql_execute_commandP3THD+0x3178)[0x557eecf1a6d8]
/usr/sbin/mysqld(_Z11mysql_parseP3THDPcjP12Parser_statebb+0x3ad)[0x557eecf2123d]
/usr/sbin/mysqld(_Z16dispatch_command19enum_server_commandP3THDPcjbb+0x217a)[0x557eecf245fa]
/usr/sbin/mysqld(_Z10do_commandP3THD+0x11c)[0x557eecf25f3c]
/usr/sbin/mysqld(_Z24do_handle_one_connectionP7CONNECT+0x1fa)[0x557eed00224a]
/usr/sbin/mysqld(handle_one_connection+0x3d)[0x557eed00232d]
pthread_create.c:0(start_thread)[0x7ffbc1cdbe65]
/lib64/libc.so.6(clone+0x6d)[0x7ffbc007c88d]

Trying to get some variables.
Some pointers may be invalid and cause the dump to abort.
Query (0x7ffb5000fdf0): ALTER TABLE wpn_usermeta CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci
Connection ID (thread ID): 134
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

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 15075 15075 processes
Max open files 1024000 1024000 files
Max locked memory 65536 65536 bytes
Max address space unlimited unlimited bytes
Max file locks unlimited unlimited locks
Max pending signals 15075 15075 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

2020-02-29 15:39:41 0 [Note] InnoDB: Using Linux native AIO
2020-02-29 15:39:41 0 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
2020-02-29 15:39:41 0 [Note] InnoDB: Uses event mutexes
2020-02-29 15:39:41 0 [Note] InnoDB: Compressed tables use zlib 1.2.7
2020-02-29 15:39:41 0 [Note] InnoDB: Number of pools: 1
2020-02-29 15:39:41 0 [Note] InnoDB: Using SSE2 crc32 instructions
2020-02-29 15:39:41 0 [Note] InnoDB: Initializing buffer pool, total size = 128M, instances = 1, chunk size = 128M
2020-02-29 15:39:41 0 [Note] InnoDB: Completed initialization of buffer pool
2020-02-29 15:39:41 0 [Note] InnoDB: If the mysqld execution user is authorized, page cleaner thread priority can be changed. See the man page of setpriority().
2020-02-29 15:39:41 0 [Note] InnoDB: Starting crash recovery from checkpoint LSN=9667569821
2020-02-29 15:39:41 0 [Note] InnoDB: Starting final batch to recover 8 pages from redo log.
2020-02-29 15:39:42 0 [Note] InnoDB: 128 out of 128 rollback segments are active.
2020-02-29 15:39:42 0 [Note] InnoDB: Removed temporary tablespace data file: "ibtmp1"
2020-02-29 15:39:42 0 [Note] InnoDB: Creating shared tablespace for temporary tables
2020-02-29 15:39:42 0 [Note] InnoDB: Setting file './ibtmp1' size to 12 MB. Physically writing the file full; Please wait ...
2020-02-29 15:39:42 0 [Note] InnoDB: File './ibtmp1' size is now 12 MB.
2020-02-29 15:39:42 0 [Note] InnoDB: Waiting for purge to start
2020-02-29 15:39:42 0 [Note] InnoDB: 10.4.11 started; log sequence number 9667573959; transaction id 4412241
2020-02-29 15:39:42 0 [Note] InnoDB: Loading buffer pool(s) from /var/lib/mysql/ib_buffer_pool
2020-02-29 15:39:42 0 [Note] Plugin 'FEEDBACK' is disabled.
2020-02-29 15:39:42 0 [Note] Server socket created on IP: '::'.
2020-02-29 15:39:42 0 [Note] /usr/sbin/mysqld: ready for connections.
Version: '10.4.11-MariaDB' socket: '/var/lib/mysql/mysql.sock' port: 3306 MariaDB Server
2020-02-29 15:39:43 0 [Note] InnoDB: Buffer pool(s) load completed at 200229 15:39:43