When I open Teams I get a message that says ‘Windows Defender Firewall has blocked some features of this app.’ What should I do? Posted on December 1, 2020 by Katie Babcock December 1, 2020 Katie Babcock A When I open Teams I get a message that says ‘Windows Defender Firewall has blocked some features of this app.’ What should I do? If you get this message, simply click Cancel and relaunch the Teams app.