The reason in my case was completely different. I was trying to open a Feed dialog automatically after page load. And 9 times of 10 it displayed this error. First, I added show_error: true
parameter as suggested by @Peter Roome, but it didn't help, displaying 104: Invalid signature
, not descriptive at all.
Then I figured out the reason. The code was in $(document).ready
jQuery function. And it seems that some facebook stuff had not yet been loaded at the point the code was to be executed. I moved the code to $(window).load
block (which is executed after all page content is loaded), and the problem has been solved.