NO_AUTO_CREATE_USER  SQL mode, the PASSWORD()  function, and the old_passwords  system variable. 

Replication from MySQL 5.7 to 8.0 of statements that refer to these removed features can cause replication failure. Applications that use any of the removed features should be revised to avoid them and use alternatives when possible, as described in Features Removed in MySQL 8.0. 

To avoid a startup failure on MySQL 8.0, remove any instance of NO_AUTO_CREATE_USER  from sql_mode  system variable settings in MySQL option files. 

Loading a dump file that includes the NO_AUTO_CREATE_USER  SQL mode in stored program definitions into a MySQL 8.0 server causes a failure. As of MySQL 5.7.24 and MySQL 8.0.13, mysqldump  removes NO_AUTO_CREATE_USER  from stored program definitions. Dump files created with an earlier version of mysqldump  must be modified manually to remove instances of NO_AUTO_CREATE_USER . 

•In MySQL 8.0.11, these deprecated compatibility SQL modes were removed: DB2 , MAXDB , MSSQL , MYSQL323 , MYSQL40 , ORACLE , POSTGRESQL , NO_FIELD_OPTIONS , NO_KEY_OPTIONS , NO_TABLE_OPTIONS . They can no longer be assigned to the sql_mode  system variable or used as permitted values for the mysqldump --compatible  option. 

Removal of MAXDB  means that the TIMESTAMP  data type for CREATE TABLE  or ALTER TABLE  is no longer treated as DATETIME . 

Replication from MySQL 5.7 to 8.0 of statements that refer to the removed SQL modes can cause replication failure. This includes replication of CREATE  statements for stored programs (stored procedures and functions, triggers, and events) that are executed while the current sql_mode  value includes any of the removed modes. Applications that use any of the removed modes should be revised to avoid them. 

•As of MySQL 8.0.3, spatial data types permit an SRID  attribute, to explicitly indicate the spatial reference system (SRS) for values stored in the column. See Section 11.4.1, “Spatial Data Types” . 

A spatial column with an explicit SRID  attribute is SRID-restricted: The column takes only values with that ID, and SPATIAL  indexes on the column become subject to use by the optimizer. The optimizer ignores SPATIAL  indexes on spatial columns with no SRID  attribute. See Section 8.3.3, “SPATIAL Index Optimization” . If you want the optimizer to consider SPATIAL  indexes on spatial columns that are not SRID-restricted, each such column should be modified: 

•Verify that all values within the column have the same SRID. To determine the SRIDs contained in a geometry column col_name , use the following query: 

SELECT DISTINCT ST_SRID( col_name ) FROM tbl_name ; 

If the query returns more than one row, the column contains a mix of SRIDs. In that case, modify its contents so all values have the same SRID. 

•Redefine the column to have an explicit SRID  attribute. 

•Recreate the SPATIAL  index. 

•Several spatial functions were removed in MySQL 8.0.0 due to a spatial function namespace change that implemented an ST_  prefix for functions that perform an exact operation, or an MBR  prefix for functions that perform an operation based on minimum bounding rectangles. The use of removed spatial functions in generated column definitions could cause an upgrade failure. Before upgrading, run mysqlcheck --check-upgrade  for removed spatial functions and replace any that you find with their ST_  or MBR  named replacements. For a list of removed spatial functions, refer to Features Removed in MySQL 8.0. 

