in 5.2.6, there has some code added for upgrade check and fix for the db issue if any during upgrade, but the detailed info only printed on console during upgrade
if you still see the issue and GUI stopped there, you may need to open a ticket and provide your 5.2.4 db, send me the ticket ID and I will follow up your ticket
That code must be REALLY slow to run or we had a LOT of errors to fix. After 10 hours, the progress bar is now sitting at 100%, though not complete enough to log in. We will let it sit overnight and update if it clears. Might be worth noting this type of event could happen, if it was in the upgrade guide, I don't recall it being called out very noticeably.
Security Analyst, Network Engineer, Part-Time Everything Else