Finding what is responsible.
THE METHOD
Remove possible causes one at a time until the problem stops. The last thing removed is responsible.
FOR PLUGIN PROBLEMS
Rename wp-content/plugins to disable everything.
If the problem stops, rename it back and disable plugins individually until it stops again.
Tedious and reliable.
FOR THEME PROBLEMS
Rename the active theme's directory. The application falls back to a default.
If the problem stops, the theme is responsible.
FOR .HTACCESS
Rename it. If the problem stops, a rule in it is responsible.
In WordPress, re-saving permalinks generates a clean one.
FOR PHP VERSION
Switch back to the previous version in cPanel > MultiPHP Manager.
FOR CACHING
Purge everything, and disable the caching plugin temporarily.
THE DISCIPLINE
Change one thing at a time and test after each.
Changing several things simultaneously makes the cause unidentifiable, and you will not know what fixed it.
