debug set in wp-config.php: true
php ver : 5.6.10
Re(installed plugin): ok
NO debug error and the system run ok.
I retry all the steps in my localhost site: no error.
Now for me it’s a mystery: this morning all backend was down.
PS: i don’t know if it can be just a my impression, but the problem seems to be at start, before activating the plugin: when i download a plugin via WordPress GUI (generally all is ok), each time i download WCP OpenWeather, the system “struggles” a lot and, after activation, crash.
I’hope to be useful for you. (Sorry i haven’t log or debug string for you)
Alexxandro.