MediaWiki internal error.

Original exception: [ZgX0xD7z46ktB-tav4f_iwAAAMs] /index.php?title=Project:About&diff=cur&oldid=8961 Error: Call to undefined method Title::getPreviousRevisionID()
Backtrace:
from /usr/home/tgwdistweb/public_html/coretech/skins/BlueSpiceCalumma/src/Controls/VersionPager.php(114)
#0 /usr/home/tgwdistweb/public_html/coretech/skins/BlueSpiceCalumma/src/Controls/VersionPager.php(67): BlueSpice\Calumma\Controls\VersionPager->makePrevHref()
#1 /usr/home/tgwdistweb/public_html/coretech/skins/BlueSpiceCalumma/src/Controls/TemplateControl.php(41): BlueSpice\Calumma\Controls\VersionPager->getTemplateArgs()
#2 /usr/home/tgwdistweb/public_html/coretech/skins/BlueSpiceCalumma/src/AlertProvider/OldVersion.php(75): BlueSpice\Calumma\Controls\TemplateControl->getHtml()
#3 /usr/home/tgwdistweb/public_html/coretech/skins/BlueSpiceCalumma/src/AlertProvider/OldVersion.php(31): BlueSpice\Calumma\AlertProvider\OldVersion->buildVersionPager()
#4 /usr/home/tgwdistweb/public_html/coretech/vendor/mwstake/mediawiki-component-alertbanners/src/Hook/SiteNoticeAfter/AddAlerts.php(122): BlueSpice\Calumma\AlertProvider\OldVersion->getHTML()
#5 /usr/home/tgwdistweb/public_html/coretech/vendor/mwstake/mediawiki-component-alertbanners/src/Hook/SiteNoticeAfter/AddAlerts.php(85): MWStake\MediaWiki\Component\AlertBanners\Hook\SiteNoticeAfter\AddAlerts->makeAlertHTML()
#6 /usr/home/tgwdistweb/public_html/coretech/vendor/mwstake/mediawiki-component-alertbanners/src/Hook/SiteNoticeAfter/AddAlerts.php(66): MWStake\MediaWiki\Component\AlertBanners\Hook\SiteNoticeAfter\AddAlerts->collectAlerts()
#7 /usr/home/tgwdistweb/public_html/coretech/vendor/mwstake/mediawiki-component-alertbanners/src/Hook/SiteNoticeAfter/AddAlerts.php(56): MWStake\MediaWiki\Component\AlertBanners\Hook\SiteNoticeAfter\AddAlerts->doProcess()
#8 /usr/home/tgwdistweb/public_html/coretech/vendor/mwstake/mediawiki-component-alertbanners/src/Hook/SiteNoticeAfter/AddAlerts.php(24): MWStake\MediaWiki\Component\AlertBanners\Hook\SiteNoticeAfter\AddAlerts->process()
#9 /usr/home/tgwdistweb/public_html/coretech/includes/HookContainer/HookContainer.php(338): MWStake\MediaWiki\Component\AlertBanners\Hook\SiteNoticeAfter\AddAlerts::callback()
#10 /usr/home/tgwdistweb/public_html/coretech/includes/HookContainer/HookContainer.php(137): MediaWiki\HookContainer\HookContainer->callLegacyHook()
#11 /usr/home/tgwdistweb/public_html/coretech/includes/HookContainer/HookRunner.php(3422): MediaWiki\HookContainer\HookContainer->run()
#12 /usr/home/tgwdistweb/public_html/coretech/includes/skins/Skin.php(1855): MediaWiki\HookContainer\HookRunner->onSiteNoticeAfter()
#13 /usr/home/tgwdistweb/public_html/coretech/includes/skins/SkinTemplate.php(342): Skin->getSiteNotice()
#14 /usr/home/tgwdistweb/public_html/coretech/includes/skins/SkinTemplate.php(146): SkinTemplate->prepareQuickTemplate()
#15 /usr/home/tgwdistweb/public_html/coretech/includes/skins/SkinTemplate.php(177): SkinTemplate->generateHTML()
#16 /usr/home/tgwdistweb/public_html/coretech/includes/OutputPage.php(2876): SkinTemplate->outputPage()
#17 /usr/home/tgwdistweb/public_html/coretech/includes/MediaWiki.php(922): OutputPage->output()
#18 /usr/home/tgwdistweb/public_html/coretech/includes/MediaWiki.php(562): MediaWiki->main()
#19 /usr/home/tgwdistweb/public_html/coretech/index.php(50): MediaWiki->run()
#20 /usr/home/tgwdistweb/public_html/coretech/index.php(46): wfIndexMain()
#21 {main}

Exception caught inside exception handler: [ZgX0xD7z46ktB-tav4f_iwAAAMs] /index.php?title=Project:About&diff=cur&oldid=8961 Error: Call to undefined method Title::getPreviousRevisionID()
Backtrace:
from /usr/home/tgwdistweb/public_html/coretech/skins/BlueSpiceCalumma/src/Controls/VersionPager.php(114)
#0 /usr/home/tgwdistweb/public_html/coretech/skins/BlueSpiceCalumma/src/Controls/VersionPager.php(67): BlueSpice\Calumma\Controls\VersionPager->makePrevHref()
#1 /usr/home/tgwdistweb/public_html/coretech/skins/BlueSpiceCalumma/src/Controls/TemplateControl.php(41): BlueSpice\Calumma\Controls\VersionPager->getTemplateArgs()
#2 /usr/home/tgwdistweb/public_html/coretech/skins/BlueSpiceCalumma/src/AlertProvider/OldVersion.php(75): BlueSpice\Calumma\Controls\TemplateControl->getHtml()
#3 /usr/home/tgwdistweb/public_html/coretech/skins/BlueSpiceCalumma/src/AlertProvider/OldVersion.php(31): BlueSpice\Calumma\AlertProvider\OldVersion->buildVersionPager()
#4 /usr/home/tgwdistweb/public_html/coretech/vendor/mwstake/mediawiki-component-alertbanners/src/Hook/SiteNoticeAfter/AddAlerts.php(122): BlueSpice\Calumma\AlertProvider\OldVersion->getHTML()
#5 /usr/home/tgwdistweb/public_html/coretech/vendor/mwstake/mediawiki-component-alertbanners/src/Hook/SiteNoticeAfter/AddAlerts.php(85): MWStake\MediaWiki\Component\AlertBanners\Hook\SiteNoticeAfter\AddAlerts->makeAlertHTML()
#6 /usr/home/tgwdistweb/public_html/coretech/vendor/mwstake/mediawiki-component-alertbanners/src/Hook/SiteNoticeAfter/AddAlerts.php(66): MWStake\MediaWiki\Component\AlertBanners\Hook\SiteNoticeAfter\AddAlerts->collectAlerts()
#7 /usr/home/tgwdistweb/public_html/coretech/vendor/mwstake/mediawiki-component-alertbanners/src/Hook/SiteNoticeAfter/AddAlerts.php(56): MWStake\MediaWiki\Component\AlertBanners\Hook\SiteNoticeAfter\AddAlerts->doProcess()
#8 /usr/home/tgwdistweb/public_html/coretech/vendor/mwstake/mediawiki-component-alertbanners/src/Hook/SiteNoticeAfter/AddAlerts.php(24): MWStake\MediaWiki\Component\AlertBanners\Hook\SiteNoticeAfter\AddAlerts->process()
#9 /usr/home/tgwdistweb/public_html/coretech/includes/HookContainer/HookContainer.php(338): MWStake\MediaWiki\Component\AlertBanners\Hook\SiteNoticeAfter\AddAlerts::callback()
#10 /usr/home/tgwdistweb/public_html/coretech/includes/HookContainer/HookContainer.php(137): MediaWiki\HookContainer\HookContainer->callLegacyHook()
#11 /usr/home/tgwdistweb/public_html/coretech/includes/HookContainer/HookRunner.php(3422): MediaWiki\HookContainer\HookContainer->run()
#12 /usr/home/tgwdistweb/public_html/coretech/includes/skins/Skin.php(1855): MediaWiki\HookContainer\HookRunner->onSiteNoticeAfter()
#13 /usr/home/tgwdistweb/public_html/coretech/includes/skins/SkinTemplate.php(342): Skin->getSiteNotice()
#14 /usr/home/tgwdistweb/public_html/coretech/includes/skins/SkinTemplate.php(146): SkinTemplate->prepareQuickTemplate()
#15 /usr/home/tgwdistweb/public_html/coretech/includes/skins/SkinTemplate.php(177): SkinTemplate->generateHTML()
#16 /usr/home/tgwdistweb/public_html/coretech/includes/OutputPage.php(2876): SkinTemplate->outputPage()
#17 /usr/home/tgwdistweb/public_html/coretech/includes/exception/MWExceptionRenderer.php(183): OutputPage->output()
#18 /usr/home/tgwdistweb/public_html/coretech/includes/exception/MWExceptionRenderer.php(102): MWExceptionRenderer::reportHTML()
#19 /usr/home/tgwdistweb/public_html/coretech/includes/exception/MWExceptionHandler.php(131): MWExceptionRenderer::output()
#20 /usr/home/tgwdistweb/public_html/coretech/includes/exception/MWExceptionHandler.php(248): MWExceptionHandler::report()
#21 /usr/home/tgwdistweb/public_html/coretech/includes/MediaWiki.php(584): MWExceptionHandler::handleException()
#22 /usr/home/tgwdistweb/public_html/coretech/index.php(50): MediaWiki->run()
#23 /usr/home/tgwdistweb/public_html/coretech/index.php(46): wfIndexMain()
#24 {main}