When pasting in any string over length 256 in a command block I am kicked with the following message:
Internal Exception: io.netty.handler.codec.DecoderException: The received string length is longer than maximum allowed (347 > 256)
Aside that, I am aware that the command block maximum input is 256 characters now, but this seriously breaks alot of maps and commands that were longer. For example, you can no longer get player heads with custom textures from here:
https://freshcoal.com/maincollection
Thank you!
This has been fixed in 18w30a (snapshot for 1.13.1).