The panel also ruled that Facebook members were not adequately informed on how the company planned to use data on their contacts.
The ruling echoed similar rulings by two lower courts in Berlin, in 2012 and 2014, according to Reuters.
Friend finder collects the email addresses of friends or contacts in users’ address books, with their permission, and uses that information to send invites to those friends and contacts who are not yet Facebook members.
A spokeswoman for Facebook in Germany told Reuters the company was still awaiting the formal decision, which it would then study “to assess any impact on our services.”
Readers: What are your thoughts on Facebook’s friend finder?