Bukkit

What steps will reproduce the problem?

I'm not quite sure what really reproduces the problem. Players reported, they were playing and after somebody had killed an other player. The big problem is, that firstly, there weren't any death messages and also, the imaginary-killed player didn't lose his inventory. They spawned at the normal PvP spawn, but kept the SG inventory and couldn't leave the arena. (An internal error occurred while attempting to perform this command.)
Well, the console was spammed... two hours (!!) full of the following message:
[13:13:50] [Thread-47/WARN]: [SurvivalGames] Error while working on tasks: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: No operations

Also, the error log after player'd been trying to leave the arena: http://pastebin.com/6KE8g6mx
Next log, after I tried to reload the lobby: http://pastebin.com/dJ5ynmBm

What version of the product are you using?
Dev 1.9.3b

Do you have an error log of what happened?
See above.

We're running on Spigot Build 1649.

I changed to SQLite again...let's see if that works.