Flex / Flash Compiler Error #1023: Incompatible override.

Posted in Adobe, Error, Error, errors, Flash, Flash 10, Flex at 10:40 pm by Curtis J. Morley

AS3 Compiler Error #1023: Incompatible override.

AS3 Error 1023 Description:

This ActionScript error is the most terse error that AS3 has provided us.  It is nothing like the beautiful description of AS3 Warning 1090

It popped up, rearing it's ugly head like a teenager on Halloween. In most cases this error has more to do with AS3 Error 1021 than it does with an "Incompatible override".   The first example below demonstrates this behavior. Example 1 will also give AS3 Error 1021 every time.

The second example is when an "Incompatible override" really is the reason.  Method signatures have to match or you will get this error.  Basically it means that you have not matched everything up properly from the method/Class that you are overriding.  So if you are overriding something that accepts events and you forget to put in events you will get this error.  If you give it a different Type you will get this error. Etc...

Adobe gives a good explanation of my second example.  They say:

"A function marked override must exactly match the parameter and return type declaration of the function it is overriding. It must have the same number of parameters, each of the same type, and declare the same return type. If any of the parameters are optional, that must match as well. Both functions must use the same access specifier (public, private, and so on) or namespace attribute as well."

Flex / Flash Error #1023 Fix:

Make sure that you do not have duplicate names with an object and a function


Match the Method Signature of the soon to be overridden class.

Bad Code 1:

var myArray:Array = [1,2,3];

function myArray () {

Good Code 1:

var myArray:Array = [1,2,3];

function myArrayFunction () {

Bad Code 2:

override protected function draw(event:Event = null):void

Good Code 2:

override protected function draw(event:Event):void

Related Errors:

AS3 Error 3596
AS3 Error 1021
AS3 Error 1023 (Different error same number)

This should help you resolve Flex / Flash Warning #1023

Thanks and as always Happy Flashing

Curtis J. Morley


  1. curtismorley.com » AS3 Compiler Error# 1021: Duplicate function definition. said,

    October 22, 2008 at 11:32 pm

    […] AS3 Error 3596 AS3 Compiler Error 1023 AS3 Error 1023 (Different error same number.  This one has nothing to do with error 1021) […]

  2. Glenn Lucas said,

    September 4, 2009 at 1:11 pm

    Saved me some time. Thanks for taking the time to post this.

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