I know, this is a really old post, but since it's google indicate and still open and would like to ask the same question.
I have the same problem and was asking myself, if there's a solution? In the error logs I see a "Handler for x-httpd-php73 returned invalid result code 70007" and "...70008". Two days ago everything worked super, I did not change any preferences or anything else.
In a J!-Forum i read, that it's a problem with my ISP? https://forum.joomla.org/viewtopic.php?t=451586 Does anybody knows more?
Thanks and best regards, Cassirer