This extension uses the ObjectCache::getMainWANInstance() method, which is deprecated, causing a fatal error when editing pages like MediaWiki:Sidebar.
Debug:
[baf2427f61302637fde6a2e1] /index.php?title=MediaWiki:Sidebar&action=submit Error from line 29 of /var/www/html/extensions/PortableInfobox/includes/services/PortableInfoboxDataService.php: Call to undefined method ObjectCache::getMainWANInstance()
Backtrace:
#0 /var/www/html/extensions/PortableInfobox/includes/services/PortableInfoboxDataService.php(39): PortableInfoboxDataService->__construct(Title)
#1 /var/www/html/extensions/PortableInfobox/includes/PortableInfobox.hooks.php(39): PortableInfoboxDataService::newFromTitle(Title)
#2 /var/www/html/includes/HookContainer/HookContainer.php(320): PortableInfoboxHooks::onPageContentSave(WikiPage, User, WikitextContent, CommentStoreComment, integer, NULL, NULL, integer, Status)
#3 /var/www/html/includes/HookContainer/HookContainer.php(131): MediaWiki\HookContainer\HookContainer->callLegacyHook(string, array, array, array)
#4 /var/www/html/includes/HookContainer/HookRunner.php(2788): MediaWiki\HookContainer\HookContainer->run(string, array)
#5 /var/www/html/includes/Storage/PageUpdater.php(768): MediaWiki\HookContainer\HookRunner->onPageContentSave(WikiPage, User, WikitextContent, CommentStoreComment, integer, NULL, NULL, integer, Status)
#6 /var/www/html/includes/page/WikiPage.php(2015): MediaWiki\Storage\PageUpdater->saveRevision(CommentStoreComment, integer)
#7 /var/www/html/includes/EditPage.php(2457): WikiPage->doEditContent(WikitextContent, CommentStoreComment, integer, boolean, User, string, array, integer)
#8 /var/www/html/includes/EditPage.php(1724): EditPage->internalAttemptSave(array, boolean)
#9 /var/www/html/includes/EditPage.php(680): EditPage->attemptSave(array)
#10 /var/www/html/includes/actions/EditAction.php(71): EditPage->edit()
#11 /var/www/html/includes/actions/SubmitAction.php(38): EditAction->show()
#12 /var/www/html/includes/MediaWiki.php(527): SubmitAction->show()
#13 /var/www/html/includes/MediaWiki.php(313): MediaWiki->performAction(Article, Title)
#14 /var/www/html/includes/MediaWiki.php(940): MediaWiki->performRequest()
#15 /var/www/html/includes/MediaWiki.php(543): MediaWiki->main()
#16 /var/www/html/index.php(53): MediaWiki->run()
#17 /var/www/html/index.php(46): wfIndexMain()
#18 {main}