MediaWiki internal error.

Original exception: [b8c83bb2759b3daafa5e9ef2] /index.php?title=User:Fumblebee&action=info Error: Failed opening required '/app/includes/specials/SpecialUserRights.php' (include_path='/app/vendor/pear/console_getopt:/app/vendor/pear/mail:/app/vendor/pear/mail_mime:/app/vendor/pear/net_smtp:/app/vendor/pear/net_socket:/app/vendor/pear/net_url2:/app/vendor/pear/pear-core-minimal/src:/app/vendor/pear/pear_exception:.:')
Backtrace:
from /app/includes/AutoLoader.php(221)
#0 /app/includes/skins/Skin.php(1452): AutoLoader::autoload()
#1 /app/includes/skins/Skin.php(1560): Skin->buildNavUrls()
#2 /app/includes/skins/SkinTemplate.php(606): Skin->buildSidebar()
#3 /app/includes/skins/SkinTemplate.php(181): SkinTemplate->getPortletsTemplateData()
#4 /app/includes/skins/SkinMustache.php(125): SkinTemplate->getTemplateData()
#5 /app/skins/Vector/includes/SkinVectorLegacy.php(161): SkinMustache->getTemplateData()
#6 /app/includes/skins/SkinMustache.php(92): MediaWiki\Skins\Vector\SkinVectorLegacy->getTemplateData()
#7 /app/includes/skins/SkinTemplate.php(174): SkinMustache->generateHTML()
#8 /app/includes/Output/OutputPage.php(2947): SkinTemplate->outputPage()
#9 /app/includes/MediaWiki.php(978): MediaWiki\Output\OutputPage->output()
#10 /app/includes/MediaWiki.php(613): MediaWiki->main()
#11 /app/index.php(50): MediaWiki->run()
#12 /app/index.php(46): wfIndexMain()
#13 {main}

Exception caught inside exception handler: [b8c83bb2759b3daafa5e9ef2] /index.php?title=User:Fumblebee&action=info Error: Failed opening required '/app/includes/specials/SpecialUserRights.php' (include_path='/app/vendor/pear/console_getopt:/app/vendor/pear/mail:/app/vendor/pear/mail_mime:/app/vendor/pear/net_smtp:/app/vendor/pear/net_socket:/app/vendor/pear/net_url2:/app/vendor/pear/pear-core-minimal/src:/app/vendor/pear/pear_exception:.:')
Backtrace:
from /app/includes/AutoLoader.php(221)
#0 /app/includes/skins/Skin.php(1452): AutoLoader::autoload()
#1 /app/includes/skins/Skin.php(1560): Skin->buildNavUrls()
#2 /app/includes/skins/SkinTemplate.php(606): Skin->buildSidebar()
#3 /app/includes/skins/SkinTemplate.php(181): SkinTemplate->getPortletsTemplateData()
#4 /app/includes/skins/SkinMustache.php(125): SkinTemplate->getTemplateData()
#5 /app/skins/Vector/includes/SkinVectorLegacy.php(161): SkinMustache->getTemplateData()
#6 /app/includes/skins/SkinMustache.php(92): MediaWiki\Skins\Vector\SkinVectorLegacy->getTemplateData()
#7 /app/includes/skins/SkinTemplate.php(174): SkinMustache->generateHTML()
#8 /app/includes/Output/OutputPage.php(2947): SkinTemplate->outputPage()
#9 /app/includes/exception/MWExceptionRenderer.php(188): MediaWiki\Output\OutputPage->output()
#10 /app/includes/exception/MWExceptionRenderer.php(105): MWExceptionRenderer::reportHTML()
#11 /app/includes/exception/MWExceptionHandler.php(134): MWExceptionRenderer::output()
#12 /app/includes/exception/MWExceptionHandler.php(251): MWExceptionHandler::report()
#13 /app/includes/MediaWiki.php(635): MWExceptionHandler::handleException()
#14 /app/index.php(50): MediaWiki->run()
#15 /app/index.php(46): wfIndexMain()
#16 {main}