MediaWiki internal error.

Original exception: exception 'ErrorPageError' with message 'The requested page title was invalid, empty, or an incorrectly linked inter-language or inter-wiki title.
It may contain one or more characters which cannot be used in titles.' in /homepages/40/d104827571/htdocs/wiki/includes/Wiki.php:178
Stack trace:
#0 /homepages/40/d104827571/htdocs/wiki/includes/Wiki.php(59): MediaWiki->initializeSpecialCases(Object(Title), Object(OutputPage), Object(WebRequest))
#1 /homepages/40/d104827571/htdocs/wiki/index.php(114): MediaWiki->initialize(Object(Title), NULL, Object(OutputPage), Object(User), Object(WebRequest))
#2 {main}

Exception caught inside exception handler: exception 'MWException' with message 'Detected bug in an extension! Hook efGoogleAnalyticsHookText failed to return a value; should return true to continue hook processing or false to abort.' in /homepages/40/d104827571/htdocs/wiki/includes/Hooks.php:137
Stack trace:
#0 /homepages/40/d104827571/htdocs/wiki/includes/Skin.php(908): wfRunHooks('SkinAfterBottom...', Array)
#1 /homepages/40/d104827571/htdocs/wiki/includes/SkinTemplate.php(401): Skin->bottomScripts()
#2 /homepages/40/d104827571/htdocs/wiki/includes/OutputPage.php(945): SkinTemplate->outputPage(Object(OutputPage))
#3 /homepages/40/d104827571/htdocs/wiki/includes/Exception.php(252): OutputPage->output()
#4 /homepages/40/d104827571/htdocs/wiki/includes/Exception.php(269): ErrorPageError->report()
#5 /homepages/40/d104827571/htdocs/wiki/includes/Exception.php(327): wfReportException(Object(ErrorPageError))
#6 [internal function]: wfExceptionHandler(Object(ErrorPageError))
#7 {main}