When moving XF to a new server, running into class errors

I am moving XF to a new a server, and I have been getting odd errors...

[Thu Jul 04 21:24:52 2013] [error] [client] PHP Fatal error: Class name must be a valid object or a string in /var/www/html/chat/library/XenForo/Search/DataHandler/Abstract.php on line 280, referer: http://**/admin.php?tools/cache-rebuild

as one example. Any suggestion as to what might be different on this server? I've got elasticsearch enabled; but I seem to have the same issue even when ES is disabled or removed.

PHP 5.2.17 (cli) (built: Mar 1 2012 16:36:14)
PHP 5.3.25 (cli) (built: May 12 2013 16:33:12)


Well-known member
Do you have/had any custom addons with a search feature?
It seems that there's still a search hander from an old addon registered.

Maybe it's your db backup? Is it a old backup?
I had an client who used a old db backup(with some installed addons) but the current filebackup hadn't the addon files, and he had run into similar problems.

Could you post the whole error message?


XenForo developer
Staff member
I'm afraid there just isn't enough information here for us to be able to act. Would you please post the entire error message including the stack trace, and any additional information that might be of use to us in working out what is going wrong?
That's all I had to see; there wasn't anything else available to me. I scped the entire dir over and a mirror of the db; so I'd be surprised if there were any file differences.

I just realized I had disabled Forumrunner badly by moving the plugin dir out of the directory. Checking to see if that was it.

Fatal error: Class 'vw_Hard_Core' not found in /var/www/html/chat/library/vw/XenForo/Search/DataHandler/Base.php on line 57

This is after Xenforo is uninstalled. Looks like the beta might still attach something? After deleting the plugin files in library (with it already installed) I get t

[Fri Jul 05 09:49:51 2013] [error] [client] PHP Fatal error: Class name must be a valid object or a string in /var/www/html/chat/library/XenForo/Search/DataHandler/Abstract.php on line 280,

No additional error message to show; nothing gets stored in the server logs component.


in memoriam 1991-2020
You removed files during your upgrade. Specifically the /vw/Hard/Core.php. I believe that is VaultWiki. Try uploading that file again.


in memoriam 1991-2020
I do not use the add-on; so I cannot help. Attempt to upload the latest files to fix the problem. That may fix it for you. (The search handler is looking for that file)


in memoriam 1991-2020
You would have to rewrite the portion of code in the Search handler. At this point, if uploading didn't fix your issue, it's best to get support from the add-on author.