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The crash happened with an indexed virtual column whose value is evaluated using a function that has a different meaning in sql_mode='' vs sql_mode=ORACLE: - DECODE() - LTRIM() - RTRIM() - LPAD() - RPAD() - REPLACE() - SUBSTR() For example: CREATE TABLE t1 ( b VARCHAR(1), g CHAR(1) GENERATED ALWAYS AS (SUBSTR(b,0,0)) VIRTUAL, KEY g(g) ); So far we had replacement XXX_ORACLE() functions for all mentioned function, e.g. SUBSTR_ORACLE() for SUBSTR(). So it was possible to correctly re-parse SUBSTR_ORACLE() even in sql_mode=''. But it was not possible to re-parse the MariaDB version of SUBSTR() after switching to sql_mode=ORACLE. It was erroneously mis-interpreted as SUBSTR_ORACLE(). As a result, this combination worked fine: SET sql_mode=ORACLE; CREATE TABLE t1 ... g CHAR(1) GENERATED ALWAYS AS (SUBSTR(b,0,0)) VIRTUAL, ...; INSERT ... FLUSH TABLES; SET sql_mode=''; INSERT ... But the other way around it crashed: SET sql_mode=''; CREATE TABLE t1 ... g CHAR(1) GENERATED ALWAYS AS (SUBSTR(b,0,0)) VIRTUAL, ...; INSERT ... FLUSH TABLES; SET sql_mode=ORACLE; INSERT ... At CREATE time, SUBSTR was instantiated as Item_func_substr and printed in the FRM file as substr(). At re-open time with sql_mode=ORACLE, "substr()" was erroneously instantiated as Item_func_substr_oracle. Fix: The fix proposes a symmetric solution. It provides a way to re-parse reliably all sql_mode dependent functions to their original CREATE TABLE time meaning, no matter what the open-time sql_mode is. We take advantage of the same idea we previously used to resolve sql_mode dependent data types. Now all sql_mode dependent functions are printed by SHOW using a schema qualifier when the current sql_mode differs from the function sql_mode: SET sql_mode=''; CREATE TABLE t1 ... SUBSTR(a,b,c) ..; SET sql_mode=ORACLE; SHOW CREATE TABLE t1; -> mariadb_schema.substr(a,b,c) SET sql_mode=ORACLE; CREATE TABLE t2 ... SUBSTR(a,b,c) ..; SET sql_mode=''; SHOW CREATE TABLE t1; -> oracle_schema.substr(a,b,c) Old replacement names like substr_oracle() are still understood for backward compatibility and used in FRM files (for downgrade compatibility), but they are not printed by SHOW any more.