"Unknown error generating output application.xml files"

I get the following error at random times when compiling an AIR app in FlexBuilder:

Unknown error generating output application.xml files

It suggests consulting the error log, which usually mentions something about the application.xml file being read-only.

The catch is, you don't need to set the main application.xml file to be read/write. You need to change the application.xml file within the bin-debug folder to have read/write privileges. After doing so, clean the project and try to run it again. It should be fine.

Note that the file application.xml is actually whatever your application name is, dot xml.