Error 506

Hi I woke up to see this message Can anybody help me with the following i cannot get into my wordpress login panel to see the problem.

Fatal error: Can’t use function return value in write context in /home2/adeoryan/public_html/learnwithadrian.com/wp-content/plugins/all-in-one-seo-pack/admin/aioseop_module_class.php on line 506

Thanks

Adrian