Caught exception publishing to page as Post…

Hmm. Anything in your debug file, or are you not running with debug?

Is it possible your token(s) expired? Something else changed on the server, like PHP version or curl version?

Suspicious that it is happening on multiple blogs at once, or did you mean on all blog posts?

It is happening on multiple blogs at once.

I tried with debug, but the file ist empty.
At last I commented out line 503 in publish_to_facebook.php
//wp_die($wpbook_message,’WPBook Error publishing to page’);
Now its working again.

Working again as in the posts actually make it to facebook, or it just quietly ignores the error?

It’s throwing an error there – the facebook response was empty, when it should have contained a post ID (which WPBook then stores in post_meta and uses to import comments down the road).

But the error message you mentioned at the start of the thread isn’t the one thrown by lne 503 – that error is thrown back on line 474, and suggests Facebook’s API returned an error.

Commenting out those lines won’t change anything about the success/failure of posting on FB side, it will just ignore the failure quietly and allow WordPress to report success.