Lumen 5.2 uses the 5.2 family of Laravel components, as well as introduces some significant changes to Lumen's underlying philosophy and purpose. It has been released on 7th January 2016. Use it in addition to the [tag:lumen] tag in questions specific to Lumen 5.2.
Only Stateless APIs
Lumen 5.2 represents a shift on slimming Lumen to focus solely on serving stateless, JSON APIs. As such, sessions and views are no longer included with the framework. If you need access to these features, you should use the full Laravel framework. Upgrading your Lumen application to the full Laravel framework mainly involves copying your routes and classes over into a fresh installation of Laravel. Since Laravel and Lumen share many of the same components, your classes should not require any modification.
Authentication
Because sessions are no longer included with Lumen, authentication must be done statelessly using API tokens or headers. You have complete control over the authentication process in the new AuthServiceProvider.
Testing Helpers
Since sessions are no longer included with Lumen, all of the form interaction testing helpers have been removed. The testing helpers for JSON APIs remain.
From Lumen 5.2 Release Notes
