Almost everyone who uses Windows has seen it. You launch an application or game, and Windows Firewall pops up and says it’s “blocked some features of this app.” What does this mean, and should you allow access?

Why Does This Message Appear?

This message appears when an application wants to act as a server and accept incoming connections. You don’t see this prompt for most applications you use, like web browsers and email clients. You only see it with specific types of applications, such as media servers, games with multiplayer features, online file-sharing tools, and other server applications.

The Windows Firewall blocks incoming connections by default. But the first time it blocks connections to a new application, this message pop up. You can then choose whether to allow the connection through. This ensures connections aren’t silently blocked without your knowledge.

On Windows 10, you see a “Windows Defender Firewall has blocked some features of this app” pop-up. On Windows 7 and 8, you see the “Windows Firewall has blocked some features of this app” message instead.

Should You Allow Access?

Windows Defender Security Alert on Windows 10.

When this box appears, you have a few choices. You can click “Allow Access” and allow incoming connections through the firewall. Or, you can click “Cancel,” and the firewall continues to block incoming connections for that application.

You can also choose which types of networks you want to allow the connections on. For example, you might allow a media server application only on private networks. That way, when you connect your laptop to public Wi-Fi, no one can connect to your media server. People on your home or work networks, however, will still be able to connect.

When you connect to a network, you choose whether it’s public or private—Windows doesn’t automatically know. You can change this option for a network later in the Control Panel or Settings app.

If you trust an application and want to use all its features, you should allow access. If you disallow access for a PC game, you might not be able to host multiplayer games. If you see this prompt and want to use a media server to share your media with other systems on your network, you likely have to allow access to do so. A BitTorrent client, for example, needs this access to upload data to other systems on the internet.

If you don’t allow access, an application might not function properly. So, you might not be able to host multiplayer games in a PC game, as the firewall blocks incoming connections.

If you don’t recognize the application, you might want to search the web for the name and find out more information. Some types of malware function as a server and might trigger a firewall alert. Run a scan with your preferred antivirus program if you’re concerned your PC might have malware.

RELATED: What's the Difference Between Private and Public Networks in Windows?

How to Allow or Disallow Access Later

The Windows Firewall doesn’t ask you twice about the same application, but you can change the setting to allow or disallow any app in the future. To do so, head to Control Panel > System and Security > Windows Defender Firewall > Allow an app or feature through Windows Defender Firewall.

Click “Change Settings” to unlock the settings. Locate the application in the list, and then click the Public or Private checkboxes to control whether it’s allowed or disallowed, respectively. If you uncheck both boxes next to an application, it won’t be allowed to connect on either Public or Private networks. If you check both boxes, the app can connect on both.

A Windows Defender Firewall allowed apps list.

How to Disable the Notifications

If you’d prefer not to see these notifications and that Windows automatically block incoming connections to all applications, you can.

To do so, head to Control Panel > System and Security > Windows Defender Firewall > Change notification settings.

To disable the notifications, uncheck the “Notify me when Windows Defender Firewall blocks a new app” option. There are two options here: one for private networks and one for public.

Uncheck the "Notify me when Windows Defender Firewall blocks a new app" option under both Private and Public Network Settings.

This window is a pretty common sight on Windows, and you’ll usually have some idea why an application wants this level of network access. In most cases, if you trust an app, it’s safe to allow. Even if you allow an application through the Windows Firewall, your router’s network address translation (NAT) still prevents many incoming connections unless you set up port forwarding.

Profile Photo for Chris Hoffman Chris Hoffman
Chris Hoffman is Editor-in-Chief of How-To Geek. He's written about technology for over a decade and was a PCWorld columnist for two years. Chris has written for The New York Times and Reader's Digest, been interviewed as a technology expert on TV stations like Miami's NBC 6, and had his work covered by news outlets like the BBC. Since 2011, Chris has written over 2,000 articles that have been read more than one billion times---and that's just here at How-To Geek.
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