Yay. I’m using Adobe AIR 3.7 merged into Flex SDK 4.6 and this error was raising on desktop and mobile at runtime. I forgot to define proper swf-version flag in my compiler settings. Here’s quick fix for FlashBuilder:
This took me about an hour, so I hope to save someone’s time.
PS. Here’s nice list of swf-versions values for different SDK configurations: -swf-versions list.