Database [] not configured Laravel 5

In my case I used 2 db connections and the second added was not cached, the command call: php artisan config:cache did the trick.

To see what's going on it was sufficient to output the $connections variable in DatabaseManager->configure method.

You're using single connection, so you don't need to specify it:

$langs = DB::table('lang')->get();

You should use connection() method only when you're working with multiple DB connections.

For me the connection worked in development but not in the production environment, so after a lot of searching, I had to rebuild the configuration cache and It has worked. I ran the following command in the laravel root directory:

php artisan config:cache