After I’ve updated to Flex SDK 3.1.0 I’ve got this Error #2046: The loaded file did not have a valid signature.
Everything in the projects was pointing to the new sdk 3.1.0, instead of 3.0.0, but RSL libraries in the bin-debug folder were still from the old SDK (framework_3.0.0.477.swf, rpc_3.0.0.477.swf, datavisualization_3.0.0.477.swf along with corresponding SWZs)
After some head scratching I’ve opened up the properties of the main application,
Flex Builder path => Library path and looked into the settings of the framework libraries -bingo! It was still using the old settings.
So, all you have to do is to remove old RSLs and add new ones (both swf & swz), so it will look like that: