Troubleshooting Laravel ‘Class log does not exist’ error

This is a common problem – the error is in Illuminate/Container/Container.php (line 736 or 741).

Forum thread

Common reason: spaces in environment variable values in .env file

Two other fixes that have worked for me:

• after an apt-get upgrade on Homestead, installing the php7.0-mbstring package fixed it (Laravel needs four PHP extensions: OpenSSL, PDO, Mbstring and Tokenizer)
• on another installation, changing syntax from:

  $app->environment('production')

  to:

  'production' === env('APP_ENV')

  in a ternary operator in config/app.php was the solution.