MediaWiki internal error.

Original exception: [269ce4ccc44cac8ebabdd619] /wiki/index.php?title=User_talk:Welcome_to_Citizendium/Archive3&action=history Error: Call to undefined method User::isLoggedIn()
Backtrace:
from /var/www/html/citiz/public_html/wiki/LocalSettings.php(315)
#0 /var/www/html/citiz/public_html/wiki/includes/HookContainer/HookContainer.php(338): efAddSkinStyles()
#1 /var/www/html/citiz/public_html/wiki/includes/HookContainer/HookContainer.php(137): MediaWiki\HookContainer\HookContainer->callLegacyHook()
#2 /var/www/html/citiz/public_html/wiki/includes/HookContainer/HookRunner.php(939): MediaWiki\HookContainer\HookContainer->run()
#3 /var/www/html/citiz/public_html/wiki/includes/OutputPage.php(2802): MediaWiki\HookContainer\HookRunner->onBeforePageDisplay()
#4 /var/www/html/citiz/public_html/wiki/includes/MediaWiki.php(926): OutputPage->output()
#5 /var/www/html/citiz/public_html/wiki/includes/MediaWiki.php(939): MediaWiki::{closure}()
#6 /var/www/html/citiz/public_html/wiki/includes/MediaWiki.php(563): MediaWiki->main()
#7 /var/www/html/citiz/public_html/wiki/index.php(53): MediaWiki->run()
#8 /var/www/html/citiz/public_html/wiki/index.php(46): wfIndexMain()
#9 {main}

Exception caught inside exception handler: [269ce4ccc44cac8ebabdd619] /wiki/index.php?title=User_talk:Welcome_to_Citizendium/Archive3&action=history Error: Call to undefined method User::isLoggedIn()
Backtrace:
from /var/www/html/citiz/public_html/wiki/LocalSettings.php(315)
#0 /var/www/html/citiz/public_html/wiki/includes/HookContainer/HookContainer.php(338): efAddSkinStyles()
#1 /var/www/html/citiz/public_html/wiki/includes/HookContainer/HookContainer.php(137): MediaWiki\HookContainer\HookContainer->callLegacyHook()
#2 /var/www/html/citiz/public_html/wiki/includes/HookContainer/HookRunner.php(939): MediaWiki\HookContainer\HookContainer->run()
#3 /var/www/html/citiz/public_html/wiki/includes/OutputPage.php(2802): MediaWiki\HookContainer\HookRunner->onBeforePageDisplay()
#4 /var/www/html/citiz/public_html/wiki/includes/exception/MWExceptionRenderer.php(157): OutputPage->output()
#5 /var/www/html/citiz/public_html/wiki/includes/exception/MWExceptionRenderer.php(76): MWExceptionRenderer::reportHTML()
#6 /var/www/html/citiz/public_html/wiki/includes/exception/MWExceptionHandler.php(107): MWExceptionRenderer::output()
#7 /var/www/html/citiz/public_html/wiki/includes/exception/MWExceptionHandler.php(202): MWExceptionHandler::report()
#8 /var/www/html/citiz/public_html/wiki/includes/MediaWiki.php(585): MWExceptionHandler::handleException()
#9 /var/www/html/citiz/public_html/wiki/index.php(53): MediaWiki->run()
#10 /var/www/html/citiz/public_html/wiki/index.php(46): wfIndexMain()
#11 {main}