To fix that I followed those steps:
1) Found the referenced foreign key:
SELECT
TABLE_NAME,
COLUMN_NAME,
CONSTRAINT_NAME,
REFERENCED_TABLE_NAME,
REFERENCED_COLUMN_NAME
FROM
INFORMATION_SCHEMA.KEY_COLUMN_USAGE
WHERE
REFERENCED_TABLE_SCHEMA = 'db_name'
AND REFERENCED_TABLE_NAME = 'table_name';
My result was:
+----------------+----------------+----------------------------------------------------------------+-----------------------+------------------------+
| TABLE_NAME | COLUMN_NAME | CONSTRAINT_NAME | REFERENCED_TABLE_NAME | REFERENCED_COLUMN_NAME |
+----------------+----------------+----------------------------------------------------------------+-----------------------+------------------------+
| amasty_fpc_log | customer_group | AMASTY_FPC_LOG_CUSTOMER_GROUP_CUSTOMER_GROUP_CUSTOMER_GROUP_ID | customer_group | customer_group_id |
+----------------+----------------+----------------------------------------------------------------+-----------------------+------------------------+
2) Remove foreign key:
ALTER TABLE `amasty_fpc_log`
DROP FOREIGN KEY `AMASTY_FPC_LOG_CUSTOMER_GROUP_CUSTOMER_GROUP_CUSTOMER_GROUP_ID`;
3) Execute the alter script (or setup:upgrade)
ALTER TABLE `customer_group` MODIFY COLUMN `customer_group_id` int(10) UNSIGNED NOT NULL AUTO_INCREMENT;
NOTE: Do a backup before executing any query on database.
NOTE2: You my loose column data after removing foreign key.
I hope it helps.