PhpStorm debug console says "this view is read only"

Sometimes this can happen for the log file that is too large. PhpStorm disables the possibility of editing it and adds “this view is read only” message.

I had the same issue with log files. Disabling all log highlight plugins (i.e. Ideolog) fixed it. They weren't highlighting anything anyway except scrollbar in green color. Hope this helps somebody.

If I'm reading your screenshot and what you wish to do correctly ... then PhpStorm version you are using is too old.

The Interactive Debug Console was added in v10 while you are using v9.0.2.

https://blog.jetbrains.com/phpstorm/2015/09/get-an-advantages-of-interactive-console-during-debugging-in-phpstorm-9-5-eap/

Upgrade your PhpStorm to the latest version -- which is 2017.1.2 right now.