It appears that prosecutors in the Sergipe state court were seeking information from WhatsApp that the Facebook owned company was unable to provide, presumably access to a user's messages.
In a statement, WhatsApp said it's "disappointed at the decision" after doing the utmost to cooperate.
The decision "punishes more than 100 million users who depend upon us to communicate themselves, run their business and more, just to force us hand over information that we don't have."
This isn't the first time a block on WhatsApp has been ordered in Brazil. On December 15th, a Sao Paulo state judge order the service shutdown for 48 hours after Facebook failed to comply with an order. That shutdown was canceled shortly afterward when another court intervened.
Notably, Judge Marcel Maia Montalvão of Sergipe state is the same judge who ordered a Facebook executive jailed for failing to comply with a block on WhatsApp. The executive was briefly jailed then freed.
More details at the link below...