Bydon

...nevermind I made a stupid mistake, I was working with two lists in the method and I was adding it to the one named "list" instead of "chunkList" Thanks for the help though

Shouldn't it still let me add a value to the new list it returns though?

I'm trying to store a String NBT tag in an NBT List, however I'm getting a "Adding mismatching tag types to tag list" when adding it to the list even though the current tag type of the list is 0 (so it should accept it and set its type to String) The code doing it is: NBTTagList chunkList = ticket.getModData().getTagList("Chunks", Constants.NBT.TAG_STRING); NBTTagString string = new NBTTagString(chunk.xPosition + "," + chunk.zPosition); System.out.println("Type: " + chunkList.func_150303_d()); list.appendTag(string); System.out.println("Type: " + chunkList.func_150303_d()); ticket.getModData().setTag("Chunks", chunkList); And the output is Type: 0 WARNING: Adding mismatching tag types to tag list Type: 0 And for the record, the println's are temporary, I would use the Logger otherwise