A blank error occurs on the webpage.-php Tutorial

A blank error occurs on the webpage of the website. a blank error occurs on the webpage of the website developed in php:
The situation is as follows:
1. non-logon and non-administrator logon, you can only use the domain name to open and view the homepage content and logon page. the other page content is blank;
2. log on to the admin account to view all the pages.

Known situations are as follows:
1. CACHE file 100%. after cleaning, the website returns to normal.

Solution:
1. what is the internal mechanism of the blank page caused by CACHE file 100%?
2. solution (the current idea is to regularly clean up expired CACHE files, ....)
3. is there any other reason besides the blank page caused by CACHE problems?
4. Why can I only open and view the homepage content and login page with a domain name without logging on as a non-administrator?

Waiting for solutions ..........

Reply to discussion (solution)

This problem may be caused by the framework you are using: Please describe your framework
It may also be the permission of the cache Directory: Please describe your OS, or give the directory 777 permission to try
It may also be a problem with the controller in the framework. Is there any debugging mode to see more problems?

The problem is not clearly stated:
1. when the CACHE directory reaches 100%, the website page becomes blank;
2. the server is linux (I am responsible for designing the program, so the server is not very clear );
3. framework: wordpress

Your understanding:
1. after the administrator logs in, every webpage of the website can be seen, and the controller in the framework should not be faulty;
2. the CACHE may not be used for administrator login.