TypeError: Error #1009: Cannot access a property or method of a null object reference – UIMovieClip

So I ran into this error again today. I first ran into it a few years ago. It happens to me when I have an asset that is created in Flash Pro and used in a Flex application. It happens when that component has focus and the whole application then loses focus and then receives focus again. The UIMovieClip class has some issues and so if you are getting this error try one of the following solutions. For either of these solutions you’ll need to put an asset on the root level of your application that extends UIMovieClip, DisplayObject or there are a few others. It has to be an object that the FocusManager instance of the main app can set the focus to. I like to use a logo or some other visual element that I can create in Flash and that will be on every view of your application (root level). What you want to do is before removing any UIMovieclip object from the display list, have the application set the focus to the logo or whatever you’re using. The first way of doing this is by adding the deactivate listener to your flex application. Then have the handler function for that set the focus. This works most of the time, but I’ve found some instances where it doesn’t. If you have text fields that have keyboard listener it doesn’t work. The way I prefer is to dispatch an event from each of my UIMovieClip objects before they are removed (I like to put it in a destroy function). That event bubbles all the way up to the app and then the app calls the function to change the focus. Here is an example:


That’s it. I hope this might help some of you from pulling your hair out. You want to keep all of the hair that you have, believe me I know.

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