- Affected version
- 1.5.15a
XenForo_Model_UserUpgrade::downgradeUserUpgrades doesn't check that $upgradeRecordIds actually has any IDs, resulting in the insert into xf_user_upgrade_expired failing if all records are in the grace period.
Manually giving a user a recurring upgrade which expires in the future, and then attempting to manually downgrade appears to easily trigger this.
Manually giving a user a recurring upgrade which expires in the future, and then attempting to manually downgrade appears to easily trigger this.