Registers to receive addon messages with a given prefix. In order for an addon to receive messages sent using SendAddOnMessage they must first register to receive messages with a given prefix. There is a soft cap of 64 prefixes on the server side, and a hard cap of 512 prefixes on the client side. Exceeding the soft cap is not recommended, but addon messages can still be received.

See also Addon-related functions.


success = RegisterAddonMessagePrefix("prefix")


  • prefix - A string of up to 16 characters used to identify a stream of messages. The prefix may contain any character except the null character ('\0'), which prematurely terminates the string, and the number of characters may not exceed 16. The string must not be empty. (string) (string)


  • success - Whether or not the prefix registration was successful. There is a limit of 512 prefixes per client, so registration could potentially fail. (boolean)