Error in MailServiceProvider after update.

[villimagg]

This happens when I do a composer update:

ErrorException: Notice: Undefined index: driver in /home/username/sites/myapp.dev/vendor/laravel/framework/src/Illuminate/Mail/MailServiceProvider.php line 79

[taylorotwell]

Yep. Update your mail configuration file!

[yadakhov]

I got the same error today and google led me here. I figure I write a comment to help others.

To resolve this issue:
Copy the latest code from laravel repo: https://raw.github.com/laravel/laravel/master/app/config/mail.php
into your application app/config/mail.php

The reason is that 'driver' was not an existing setting in an older version of Laravel. Using composer update only updates the class in the vendor folder but doesn't update your mail.php config file.