When enabling RCFeed ( $wgRCFeeds ) and PHP doesn't have the php-sockets extension, if you save an edit, it gets saved but no entry is inserted in the recent changes table. It doesn't add a job to update it neither.
Hopefully the debug log displays this information (this happens with a udp URL at least):
[error] [31c24f9a84f1fe30a76eaa4c] /index.php?title=Hijo&action=submit ErrorException from line 66 of /home/www/lib/mediawiki-1.30.0/includes/libs/UDPTransport.php: PHP Notice: Use of undefined constant AF_INET - assumed 'AF_INET'
#0 /home/www/lib/mediawiki-1.30.0/includes/libs/UDPTransport.php(66): MWExceptionHandler::handleError(integer, string, string, integer, array)
#1 /home/www/lib/mediawiki-1.30.0/includes/rcfeed/UDPRCFeedEngine.php(33): UDPTransport::newFromString(string)
#2 /home/www/lib/mediawiki-1.30.0/includes/rcfeed/FormattedRCFeed.php(66): UDPRCFeedEngine->send(array, string)
#3 /home/www/lib/mediawiki-1.30.0/includes/changes/RecentChange.php(432): FormattedRCFeed->notify(RecentChange, NULL)
#4 /home/www/lib/mediawiki-1.30.0/includes/changes/RecentChange.php(354): RecentChange->notifyRCFeeds()
#5 /home/www/lib/mediawiki-1.30.0/includes/changes/RecentChange.php(629): RecentChange->save()
#6 [internal function]: RecentChange::{closure}()
#7 /home/www/lib/mediawiki-1.30.0/includes/deferred/MWCallableUpdate.php(30): call_user_func(Closure)
#8 /home/www/lib/mediawiki-1.30.0/includes/deferred/DeferredUpdates.php(257): MWCallableUpdate->doUpdate()
#9 /home/www/lib/mediawiki-1.30.0/includes/deferred/DeferredUpdates.php(210): DeferredUpdates::runUpdate(MWCallableUpdate, Wikimedia\Rdbms\LBFactorySimple, string, integer)
#10 /home/www/lib/mediawiki-1.30.0/includes/deferred/DeferredUpdates.php(131): DeferredUpdates::execute(array, string, integer)
#11 /home/www/lib/mediawiki-1.30.0/includes/MediaWiki.php(895): DeferredUpdates::doUpdates(string)
#12 /home/www/lib/mediawiki-1.30.0/includes/MediaWiki.php(719): MediaWiki->restInPeace(string, boolean)
#13 /home/www/lib/mediawiki-1.30.0/includes/MediaWiki.php(740): MediaWiki->{closure}()
#14 /home/www/lib/mediawiki-1.30.0/includes/MediaWiki.php(553): MediaWiki->doPostOutputShutdown(string)
#15 /home/www/lib/mediawiki-1.30.0/index.php(43): MediaWiki->run()
#16 {main}
[fatal] [bb713578] PHP Fatal Error: Call to undefined function socket_create()MediaWiki should probably check for socket_create if $wgRCFeeds is set, and fail early (prevent the save at all), or catch the error, log it and continue without breaking all jobs that need to be inserted.