Warning: realpath() [function.realpath]: Unable to access / Plesk issue

I've just upgraded my server to version 9.3 of plesk from parallels. Now all my joomla sites ( and others) are showing a

Warning: realpath(开发者_如何学运维) [function.realpath]: Unable to access / "file location" error.

Any ideas what I can do to resolve it??

thanks

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I had the same problem with Joomla. I fixed it by turning off safe mod in php.ini.