I got errors when enable Facebook Platform
 

I have that error above my page when enabled facebook platform in facebook settings.

And below the page:
How can I fix this?:mad:

You need to replace the missing file to start with also what vb version u using

4.2.2
What missing file?

this one that says it is missing check server error logs for more info

So?

You need to make sure that you upload the facebook.php file via FTP here: includes/facebook so the pathway would look like this: includes/facebook/facebook.php What that error is telling you is that the file itself is missing, it cannot find it where its supposed to be. So more and likely if you upload the file to the place its supposed to be you will not get that warning anymore.

The issue here is that his session storage path is not writeable. He needs to fix it, or his webhost does.

One of his problems not the only one

Per his error messages, that is the one and only issue here.

The missing file makes two as I said more than one problem

Which is a temporary session file in the temp dir. It is just one issue ;)

Or how would you go about uploading the missing file /home/***/tmp//sess_049b4b10fabe8f735fce3255f17bebfa, O_RDWR?

The tmp directory/partition is probably full.

The tmp directory being full might be something, but the server wouldn't be performing well/at all if that was the case, at least long term.

I'm still nearly positive that he doesn't have permission to write to that folder.

Are you on godaddy by any chance? You should request to move to one of their new cPanel Linux accounts.

Ohh dude, there wasn't tmp folder in my home. I create a new folder and set permission 755. Errors gone, but facebook platform is not working :S

That doesn't address the issues with facebook retiring their api that the vBulletin 4 stuff was built on. There is not currently a fix.

Sorry for my bad english.
Is there a problem with facebook-vbulletin connection?

Yes facebook changed the API needed by vBulletin to connect to it, so it no longer works.