Upgrade to CiviCRM 4.3 failing on DROP FOREIGN KEY

Question

I have successfully upgraded many other CiviCRM installations over the years, but I've been unable to work my way through this issue so far.

• Ubuntu 14.04
• MySQL 5.7.23
• Apache/2.4.7
• PHP Version 5.6.37
• Drupal 7.59
• CiviCRM 4.2.20

I am trying to upgrade CiviCRM 4.2.20 to 4.3.11. Ultimately the goal is to get to 4.6 LTS. I have tried repairing the CiviCRM schema (this database has only 2 custom fields), and I've also tried the SET foreign_key_checks = 0; work around on importing the db, but I've still been unsuccessful at upgrading. I always hit this error at the stage of:

[Error: Upgrade DB to 4.3.alpha1]

ALTER TABLE civicrm_membership_type DROP FOREIGN KEY FK_civicrm_membership_autorenewal_msg_id [nativecode=1091 ** Can't DROP 'FK_civicrm_membership_autorenewal_msg_id'; check that column/key exists]

I found a helpful thread somewhere that suggesting that MySQL 5.5 may have been the culprit, so I upgraded to MySQL 5.7, and still get the exact same error regardless of MySQL version. I have a fresh export and backups, so every time I try something it is with a fresh working version of the database on 4.2.20. Any help is greatly appreciated!

Thank you,
--Tony

Update Based on Jon G's suggestion I tried commenting out the offending lines in CRM/Upgrade/Incremental/php/FourThree.php, reloaded a fresh database for upgrading, but still continued to receive the exact same error. The only difference this time being, after I hit refresh to try and force the upgrade to continue, then another message occurred:

ALTER TABLE civicrm_premiums ADD COLUMN premiums_nothankyou_position int(10) unsigned DEFAULT '1' [nativecode=1060 ** Duplicate column name 'premiums_nothankyou_position']

I couldn't grep any more lines to comment out of the FourThree.php upgrade file, and wasn't sure how this would affect database integrity. The suggested threads (CRM-12458, CRM-11260) seem to relate, but I was ultimately unable to use the information to solve this issue, admittedly due to the lack in my technical understanding.

Answer 1

This appears to be identical to CRM-12458. Which is unusual - most cases where you'd get this error were solved in CRM-11260 but there are still edge cases that can cause this.

I would read those links in full - but my guess is you should edit CRM/Upgrade/Incremental/php/FourThree.php. Remove the four highlighted lined at this link - that is, lines 883-886.

Since you're dropping a foreign key constraint that doesn't exist, there should be no difference as a result of removing these lines. Note that you may have to remove some of the following lines if you get similar errors.