FORCE 

This option controls whether and how the server performs an automatic upgrade at startup. Automatic upgrade involves two steps: 

•Step 1: Data dictionary upgrade. 

This step upgrades: 

•The data dictionary tables in the mysql  schema. If the actual data dictionary version is lower than the current expected version, the server upgrades the data dictionary. If it cannot, or is prevented from doing so, the server cannot run. 

•The Performance Schema and INFORMATION_SCHEMA . 

•Step 2: Server upgrade. 

This step comprises all other upgrade tasks. If the existing installation data has a lower MySQL version than the server expects, it must be upgraded: 

•The system tables in the mysql  schema (the remaining non-data dictionary tables). 

•The sys  schema. 

•User schemas. 

For details about upgrade steps 1 and 2, see Section 2.11.3, “What the MySQL Upgrade Process Upgrades” . 

These --upgrade  option values are permitted: 

• AUTO 

The server performs an automatic upgrade of anything it finds to be out of date (steps 1 and 2). This is the default action if --upgrade  is not specified explicitly. 

• NONE 

The server performs no automatic upgrade steps during the startup process (skips steps 1 and 2). Because this option value prevents a data dictionary upgrade, the server exits with an error if the data dictionary is found to be out of date: 

[ERROR] [MY-013381] [Server] Server shutting down because upgrade is required, yet prohibited by the command line option ’--upgrade=NONE’. [ERROR] [MY-010334] [Server] Failed to initialize DD Storage Engine [ERROR] [MY-010020] [Server] Data Dictionary initialization failed. 

• MINIMAL 

The server upgrades the data dictionary, the Performance Schema, and the INFORMATION_SCHEMA , if necessary (step 1). Note that following an upgrade with this option, Group Replication cannot 

