Laravel application problem on Ubuntu 18.04.2 LTS‬ with Plesk Onyx 17.8.11 Update Nr. 42

I have got a vserver with Ubuntu 18.04.2 LTS‬ and Plesk Onyx 17.8.11 Update Nr. 42 and PHP 7.2 FastCGI Process Manager (PHP 7.2.15 by OS vendor).

On that server I have installed a Laravel 5.7 application. In Plesk, the domain for that particular website points to a directory httpdocs/public (/var/www/vhosts/domain.tld/httpdocs/public) underneath the associated website. I only have that one domain with two other subdomains registered in Plesk.

From time to time it happens that my website is not reachable anymore. In the error_log (found in /var/www/vhosts/domain.tld/logs) there is just the following error

[date] [proxy_fcgi:error] [pid 24975:tid 140420147222272] (70007)The timeout specified has expired: [client xxx] AH01075: Error dispatching request to : (polling)

I took a look at other log files. But nothing relevant in there.

When I let Plesk point the domain to the directory httpdocs only and I create a file with name index.php in that directory (root directory of my Laravel installation), that particular file will be shown for the domain.

After that I let Plesk again point to directory httpdocs/public. Now, the website is available again!

What is going on here? Do you have any hints for me to do such that this strange behavior does not appear anymore?

Thanks a lot in advance.

via Chebli Mohamed