Hi again,
I've more information about the problem.
With no changes at all still there are posts that are published in facebook with images and others don't.
This starts suddenly with no changes except a traffic increment.
Trying with facebook tools/debug don't show erros but still trying again shows error 500.
Then could it be posible that error is when sending post to facebook the returns a 500 error code and then only is visible the link to post?
Is there any way to avoid or delay publishing if error 500 is returned?
We're moving to another webserver and i think this should end with the problem but it would be great some control over this kind of erros if posible :)
Thanks,