This is a different set of errors that that which occurs when doing large number of clones, but it has the same results.

Multiple Fill/Replace triggers massive numbers of different Netty Errors. This winds up randomly kicking all but one player on the server when it happens.

The commands do fill/replace across multiple instances of 32K blocks, there is a /stats command, and some scoreboard operations on each fill. Repeat this pattern a large number of times for different blocks/areas, and you reproduce the problem.

I get:

[16:21:22] Netty Epoll Server IO #1/ERROR: io.netty.util.IllegalReferenceCountException: refCnt: 0

[16:21:21] Netty Epoll Server IO #1/ERROR: io.netty.util.IllegalReferenceCountException: refCnt: 0, decrement: 1

[16:21:22] Netty Epoll Server IO #2/ERROR: io.netty.util.IllegalReferenceCountException: refCnt: 0, decrement: 1

[16:16:32] Netty Epoll Server IO #2/ERROR: io.netty.util.IllegalReferenceCountException: refCnt: 0

Netty Epoll Server IO #4/ERROR: io.netty.util.IllegalReferenceCountException: refCnt: 0

[16:17:41] Netty Epoll Server IO #4/ERROR: io.netty.util.IllegalReferenceCountException: refCnt: 0, decrement: 1

[16:17:40] Netty Epoll Server IO #4/ERROR: java.lang.IndexOutOfBoundsException: readerIndex: 38016 (expected: 0 <= readerIndex <= writerIndex(19008))

Netty Epoll Server IO #5/ERROR: io.netty.util.IllegalReferenceCountException: refCnt: 0, decrement: 1

[16:21:33] Netty Epoll Server IO #6/ERROR: io.netty.util.IllegalReferenceCountException: refCnt: 0

[16:21:33] Netty Epoll Server IO #6/ERROR: java.lang.IndexOutOfBoundsException: readerIndex: 25738 (expected: 0 <= readerIndex <= writerIndex(12869))

[16:24:20] Netty Epoll Server IO #8/ERROR: io.netty.util.IllegalReferenceCountException: refCnt: 0

[16:24:20] Netty Epoll Server IO #8/ERROR: io.netty.util.IllegalReferenceCountException: refCnt: 0, decrement: 1

[16:25:08] Netty Epoll Server IO #8/ERROR: java.lang.IndexOutOfBoundsException: readerIndex: 25738 (expected: 0 <= readerIndex <= writerIndex(12869))

[16:17:39] Netty Epoll Server IO #18/ERROR: io.netty.util.IllegalReferenceCountException: refCnt: 0

[16:25:08] Netty Epoll Server IO #19/ERROR: java.lang.IndexOutOfBoundsException: readerIndex: 38016 (expected: 0 <= readerIndex <= writerIndex(19008))