My upgrade to 1.5.0 didn't go well. The sync got stuck at a certain block and would not go further.

The only thing that worked for me was to backup my wallet. Completely remove the JackPot Coin wallet by uninstalling and deleting the jackpot folder in %AppData%\JackpotCoin, and the reinstalling the wallet. I then had to recreate the jackpot.conf using the information from page one of this post. The last step was to copy my wallet.dat file to the jackpot folder that I keep on my desktop.

After I started the client, it started syncing but took at least 10 hours to complete. There were no errors. Not the best experience but it worked.