Failed to connect to server don’t know what this means

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  • I’ve been trying to connect to my server but I keep getting the message:


    Internal Exception: io.netty.handler.codec.DecoderException:java.lang.IndexOutOfBoundsException: readerIndex(31)+length(1) exceeds writerIndex(31): PooledUnsafeDirectByteBuf(ridx: 31, widx: 31, cap: 31)


    I’m not really good at reading this sort of thing and all the info I found was on Index: 25, Size: 5 so I didn’t really know where to go. For context, it all started a few weeks ago when I added Alex’s Mobs (1.19) to my server and downloaded it on cursed forge. One of my friends was able to hop in, however I and my other friend weren’t. Yesterday I updated my server to Forge 1.19 (41.0.105) and downloaded all the latest versions of each of my mods, including Alex’s Mobs. However it still gives me the same message. I don’t know if its a problem on my part or something to do with the software but I’d appreciate help.


    Here’s an image of the code.

  • MysticMungus

    Changed the title of the thread from “Failed to connect to server. Internal Exception: io.netty.handler.codec...” to “Failed to connect to server don’t know what this means”.