I had similar error during CREATE USER query.
I did following solution to rectify the user table.
ALTER TABLE `user` ADD `Create_tablespace_priv` ENUM('N','Y') NOT NULL DEFAULT 'N' AFTER `Trigger_priv`;
ALTER TABLE `user` ADD `plugin` CHAR(64) NULL AFTER `max_user_connections`;
ALTER TABLE `user` ADD `authentication_string` TEXT NULL DEFAULT NULL AFTER `plugin`;
ALTER TABLE `user` ADD `password_expired` ENUM('N','Y') NOT NULL DEFAULT 'N' AFTER `authentication_string`;
Now CREATE USER query works fine.!!
Rectification is achieved from the reference of the answer to Cannot GRANT privileges as root.
Thank you RolandoMySQLDBA.!
Following helped to create above SQL:
+------------------------+------------------------+-----------------------------------+------+-----+---------+
| Field (MySQL 5.1) | Field (MySQL 5.6) | Type | Null | Key | Default |
+------------------------+------------------------+-----------------------------------+------+-----+---------+
| Host | Host | char(60) | NO | PRI | |
| User | User | char(16) | NO | PRI | |
| Password | Password | char(41) | NO | | |
| Select_priv | Select_priv | enum('N','Y') | NO | | N |
| Insert_priv | Insert_priv | enum('N','Y') | NO | | N |
| Update_priv | Update_priv | enum('N','Y') | NO | | N |
| Delete_priv | Delete_priv | enum('N','Y') | NO | | N |
| Create_priv | Create_priv | enum('N','Y') | NO | | N |
| Drop_priv | Drop_priv | enum('N','Y') | NO | | N |
| Reload_priv | Reload_priv | enum('N','Y') | NO | | N |
| Shutdown_priv | Shutdown_priv | enum('N','Y') | NO | | N |
| Process_priv | Process_priv | enum('N','Y') | NO | | N |
| File_priv | File_priv | enum('N','Y') | NO | | N |
| Grant_priv | Grant_priv | enum('N','Y') | NO | | N |
| References_priv | References_priv | enum('N','Y') | NO | | N |
| Index_priv | Index_priv | enum('N','Y') | NO | | N |
| Alter_priv | Alter_priv | enum('N','Y') | NO | | N |
| Show_db_priv | Show_db_priv | enum('N','Y') | NO | | N |
| Super_priv | Super_priv | enum('N','Y') | NO | | N |
| Create_tmp_table_priv | Create_tmp_table_priv | enum('N','Y') | NO | | N |
| Lock_tables_priv | Lock_tables_priv | enum('N','Y') | NO | | N |
| Execute_priv | Execute_priv | enum('N','Y') | NO | | N |
| Repl_slave_priv | Repl_slave_priv | enum('N','Y') | NO | | N |
| Repl_client_priv | Repl_client_priv | enum('N','Y') | NO | | N |
| Create_view_priv | Create_view_priv | enum('N','Y') | NO | | N |
| Show_view_priv | Show_view_priv | enum('N','Y') | NO | | N |
| Create_routine_priv | Create_routine_priv | enum('N','Y') | NO | | N |
| Alter_routine_priv | Alter_routine_priv | enum('N','Y') | NO | | N |
| Create_user_priv | Create_user_priv | enum('N','Y') | NO | | N |
| Event_priv | Event_priv | enum('N','Y') | NO | | N |
| Trigger_priv | Trigger_priv | enum('N','Y') | NO | | N |
| | Create_tablespace_priv | enum('N','Y') | NO | | N |
| ssl_type | ssl_type | enum('','ANY','X509','SPECIFIED') | NO | | |
| ssl_cipher | ssl_cipher | blob | NO | | NULL |
| x509_issuer | x509_issuer | blob | NO | | NULL |
| x509_subject | x509_subject | blob | NO | | NULL |
| max_questions | max_questions | int(11) unsigned | NO | | 0 |
| max_updates | max_updates | int(11) unsigned | NO | | 0 |
| max_connections | max_connections | int(11) unsigned | NO | | 0 |
| max_user_connections | max_user_connections | int(11) unsigned | NO | | 0 |
| | plugin | char(64) | YES | | |
| | authentication_string | text | YES | | NULL |
| | password_expired | enum('N','Y') | NO | | N |
+------------------------+------------------------+-----------------------------------+------+-----+---------+
