[Flex] Invalid Embed directive in stylesheet

Solution found here: http://viconflex.blogspot.com/2008/04/invalid-embed-directive-in-stylesheet.html

What ended up being the root cause of our problem is that in several places in the application we were referencing image assets directly in our assets folder, i.e. /assets/delete.png, which is often the case when our designers aren't keeping up with asset creation and developers just throw some image up as a placeholder for the time being. Now it just so happened that ONE of these references was incorrect and its Embed pointed to a file that did not exist. I discovered this when I commented out our style css references in the application, and saw the error only then. It was this broken reference that caused the above error. I fixed the reference to point to the right file, did a Project clean, and all the Invalid Embed Directive errors went away.

I should note that we had over 100 references to symbols in our css, and by default Flexbuilder only shows the first 100 errors. Unluckily the "unable to resolve 'assets/deleted.png' for transcoding in ...." was error number 138 and did not show up in the list. I had to change my preferences to show all 138 errors.

So the lesson learned is that when you get spammed with this error, it could well be that only one Embed tag somewhere in your app is actually broken, and that your css and swf is probably just fine.

To change the preferences:

In the Problems Pane, top right corner is a downward pointing triangle. Click on this to get a menu from which you can select Preferences.