Recently I had a problem on one of my WordPress websites. When trying to add a new page I could not click in the text area. Also when looking at the textarea on an already published page the text was white on white and the uttons above the text area were not showing.

At first I thought this might be a theme problem as I have had something similar with Avada after a WordPress update. I was using the Enfold theme. This is what I did.

Test theme
Changed to Twenty Fourteen theme to see if different theme solved the problem.
Sill not working.

Test Plugins.
Deactivated all plugins to see if a plugin conflict was causing the problem.

Check WordPress
In the right menu at the top. Dashboard. Updates. Re-install WordPress.
Still not working.

Change a line of code.
Following advice from a WordPress forum. I added this code

define(‘CONCATENATE_SCRIPTS’, false );

to the bottom of the wp-config.php file (just before the require_once line).

WORKED. PROBLEM SOLVED.

See pic below