The error message is printed in plain English on the top of the crash log, failure to read (as well as understand) it will leave the server inoperable. Shaders Shaders (loaded by either Optifine, Iris or otherwise) will in all likelihood break when a gun is held. This is because ...
This year's april fools included a randomly spawning ore for every single item in the game. If you're serious about playing survival or running a server, I suggest turning the ore off (config R00, set amount to 0) Added Asbestos caves Take a deep breath Sulfuric acid Generates in sulfur...