Here’s what I’m using:
The issue is unaffected by Sponge. The same thing was happening before I migrated to Sponge. Everything works perfectly fine otherwise. I run a server with a bunch of friends, I just end up having to restart the server about every 4 hours if people are trying to join due to what is essentially this:
WARNING: Failed to re-register a Channel to the new Selector.
java.lang.ClassCastException: io.netty.channel.nio.SelectedSelectionKeySetSelector cannot be cast to java.nio.channels.spi.AbstractSelector
at java.nio.channels.spi.AbstractSelectableChannel.register(Unknown Source)
at java.lang.Thread.run(Unknown Source)
after which no players can connect to the server (but most players already on the server can keep playing!).
To get further info, I’m currently running a control server with the same version of Sponge and Forge, but without any mods or plugins installed. I essentially just have to wait a while to see if the error occurs. I have a pretty good feeling that it’s as stated in the mojang bugs thread, a vanilla issue with 1.12.2 that only affects certain OS versions/kernels/I don’t really understand exactly.