After upgrading from MariaDB 10.1.32 to MariaDB 10.3.9 on one production server (several others did not encounter this problem), the server failed to start with the following problem:
2018-09-26 01:40:31 0x7f1a0dc088c0 InnoDB: Assertion failure in file /home/buildbot/buildbot/padding_for_CPACK_RPM_BUILD_SOURCE_DIRS_PREFIX/mariadb-10.3.9/storage/innobase/pars/pars0pars.cc line 818
InnoDB: Failing assertion: sym_node->table != NULL
We managed to start MariaDB by using "innodb_force_recovery = 3" and move all data to other database servers. However a drop database command causes the same issue to appear, even with the recovery on 3.
A "mysqlcheck --all-databases" did not find any issues and a mysqldump of all databases also did not cause any problems. This is the reason we think this might be a bug and not just data corruption.
Enclosed are 2 problem traces. The MariaDB-pars0pars.cc-818-first.txt contains the problem just after starting the server in 3.1.9. The second contains the problem with innodb_force_recovery = 3 after a database drop was executed. It failed a few times after the database drop and then started again correctly.