Here is randomly warn spamming into console errors about SQL leak connection/

Pastebin
https://pastebin.com/4jcxLBNb

Please complete the following information:

• Resource Version and Build Number: 5.2.1-RELEASE-b678
• Server Version PaperSpigot 1.12.2

Additional context
Cannot get steps to reproduce, but in console logs it is very common warn

ty!

I would reference the existing issue number but I can't quite remember which one it was but anyways, this is already fixed in the latest snapshot so all you need to do is update.

Link: https://ci.craftationgaming.com/job/ItemJoin/710
Remember to remove your old ItemJoin.jar file

will it be compatible with 1.12.2 server core?

Yes,
All ItemJoins versions are backward compatible with the latest Minecraft version which is currently 1.7 - 1.16.5 so that includes 1.12.2.

It has been tested as working on 1.12.2 and is slated to be a release candidate so if you encounter any issues, please let me know.