My company has 3 different websites for different business, which has been built 4 years ago. All 3 website has been built in Wordpress but part of them are also non-Wordpress.
We had no problem for any of the site for more than 3 years. And we have not changed the code. But this issue is very recent. since last May . In April we have upgraded the PHP version from 5.3 to 7.2 in our server. After 3 weeks of doing that upgrade we have started experiencing this very weird type of issue for the first time
This issue does not happen at the same time for 3 sites and doesn’t happen always. But sometimes suddenly it struck from nowhere. When this struck the affected site becomes unresponsive. It does not show any error or display any page. The spinning –grey circle (in the browser tab) spins extremely slow and waits for the webpage to load. But page does not load. It seems the site is just hanged (see screenshot). And just like a hanged pc / device we can bring the site back to normal and if we restart the Web server. After restart the site acts normally.
Our server administrator cannot see any error in the error logs. Only thing he notices is when this problem happens the server starts to use lots of memory and the number of process used starts to increase. So to fix this issue we have came to a temporary solution by setting a limit for maximum process = 50. httpd restarts if it reaches the maximum process.
We want to stop this problem permanently but totally clueless about the cause of this problem and trying to understand where to start.
My questions are
Is it a more like server issue or PHP compatibility or Wordpress issue?
We update the Wordpress and installed plugins regularly. But as the theme used is a custom made theme and have been built 4 years ago they have not been updated. Can this be a reason for the issue?
The codes in the “api” folder are also written 3 years ago. And recently we have updated our PHP version from 5.3 to 7.2 for that site in our NodeWorx. Can this be a reason?
Can it be any sort of attack by some hacker.
Please any suggestion will be appreciated.
Please Note: / FYI
These websites are also connected with one of our central database apart from their own individual “Wordpress” database. Under root “html” folder along with “wp-content”; “wp-admin” and “wp-include” folder there is also an “api” folder, which contains the customized code to connect with the central database and logic to display and insert data in there.
There are also some customized codes which has been written under the website theme i.e. “wp-content/themes/ website-theme” folder inside different files (e.g; shortcodes.php; members.php; etc.). The themes for these three website are also custom built themes.
This issue is exclusive only to these 3 sites. All other sites run smoothly.