I'm upgrading a CiviCRM 4.6.20 install to 4.7.10. I'm on Drupal 7.50. I've tried the updgrade several times. My Drupal database updates are all executed. Before running the upgrade, the civicrm_action_schedule table has an INDEX with the name, FK_civicrm_action_schedule_mapping_id. But when I execute SQL to list all foreign key constraints, there are none. I don't know if this makes a difference, but the table is empty. I don't have any rows in civicrm_action_schedule.
What could I be missing here? Thanks!
[Error: Upgrade DB to 4.7.alpha1: SQL]
Error Field Error Value
Type DB_Error
Code -4
Message DB Error: not found
Mode 16
UserInfo ALTER TABLE civicrm_action_schedule
DROP FOREIGN KEY FK_civicrm_action_schedule_mapping_id
[nativecode=1091 ** Can't DROP 'FK_civicrm_action_schedule_mapping_id'; check that column/key exists]
DebugInfo ALTER TABLE civicrm_action_schedule
DROP FOREIGN KEY FK_civicrm_action_schedule_mapping_id
[nativecode=1091 ** Can't DROP 'FK_civicrm_action_schedule_mapping_id'; check that column/key exists]