After installing Habitat for Sitecore on local development environment form https://github.com/HedgehogDevelopment/Habitat/tree/TDS-latest (scroll down for installation instructions), it found that site’s pages gives below error:

Server Error in '/' Application.
Value cannot be null.
Parameter name: source
Description: An unhandled exception occurred.

Exception Details: System.ArgumentNullException: Value cannot be null.
Parameter name: source

Source Error:

Line 64: private IEnumerable GetHistoricalOutcomes()
Line 65: {
Line 66: return this.outcomeManager.GetForEntity(new ID(Tracker.Current.Contact.ContactId));
Line 67: }

The solution is set the value of Xdb.Tracking.Enabled to false in C:\websites\Habitat.dev.local\Website\App_Config\Include\Sitecore.Xdb.config file

Hit the refresh in browser for the habitat page and bang.

Here I am assuming, the local environment is configured as CMS-only mode.