#1075 - Incorrect table definition; there can be only one auto column and it must be defined as a key in MySQL

#1075 - Incorrect table definition; there can be only one auto column and it must be defined as a key with auto increment in MySQL

The problem in this case is that the auto increment field must be a key and you are trying to drop the key. You can fix this by removing the auto increment from the field.

ALTER TABLE table_name MODIFY column_name data_type