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Fix a Mac firewall that blocks app

We'll confirm the app is blocked, open System Settings Firewall, add the app in Firewall Options, and rule out stealth mode—or tell you when to contact IT.

Troubleshooting · Home maintenance
5–15 min
What you'll need
  • Mac with admin access
  • The app that is blocked
Step 1 of 6

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Quick triage — pick your path

Choose the option that matches what you see. You can jump straight to that section.

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Steps

Goal: Confirm the app is blocked, open System Settings Firewall, add the app in Firewall Options, and rule out stealth mode.

  • Run the app and try the action that fails (e.g. connect to a server, sync). If macOS shows a prompt asking to allow or block the app, the firewall is involved.
  • Good: You see a firewall prompt or the app times out—proceed to Open Firewall Options.
  • Bad: The app works—no firewall issue.

Add app in Firewall Options

Goal: Add the blocked app to the allowed list.

  • Click the Apple menu → System Settings. On macOS Ventura or later: Network → Firewall. On older macOS: Security & Privacy → Firewall.
  • Click Firewall Options (or “Open”). Enter admin password if prompted.
  • Click the plus (+) button and browse to the app (usually in Applications). Select it and click Add. Set the app to “Allow incoming connections.”
  • Good: The app is in the list with Allow. Restart the app and test—it should connect.
  • Bad: Options is grayed out or locked—the Mac may be managed. See When to get help.

Stealth mode

Goal: Rule out stealth mode blocking the app.

  • In Firewall Options, if “Enable stealth mode” is checked, uncheck it. Some apps fail when stealth mode is on.
  • Restart the app and test.
  • Good: The app connects.
  • Bad: Still fails—check for Little Snitch or other third-party firewalls, or contact IT.

When to get help

  • You cannot open Firewall Options or changes do not stick (managed Mac).
  • You use Little Snitch or another firewall and are unsure how to allow the app.
  • The app is allowed and stealth mode is off but it still fails—the problem may be elsewhere (network, server, VPN).

Verification

  • The app appears in Firewall Options with “Allow incoming connections.”
  • The app connects or completes the action that previously failed.
  • No firewall prompt appears when you run the app.

Escalation ladder

Work from the device outward. Stop when the problem is fixed.

  1. Confirm symptom Verify the app fails to connect or you see a firewall prompt.
  2. Firewall Options Add the app to the allowed list in System Settings → Firewall Options.
  3. Stealth mode Turn off stealth mode if the app is allowed but still fails.
  4. Third-party firewall Check Little Snitch or other firewalls for blocking rules.
  5. Contact IT On managed Macs, IT must allow the app via policy.

What to capture if you need help

Before calling support or posting for help, have these ready. It speeds everything up.

  • App name and version
  • Whether you see a firewall prompt
  • Whether Firewall Options is locked or grayed out
  • Steps already tried

Does the app fail to connect or show a firewall prompt?

Run the app and try the action that fails. Look for a macOS prompt asking to allow or block.

Run the app and try the connection. Good: you see a firewall prompt or the app times out—firewall may be blocking. Bad: the app works—no firewall issue.

Yes No

You can change your answer later.

Can you open Firewall Options?

System Settings → Network → Firewall → Firewall Options. On managed Macs this may be locked.

Open System Settings → Network → Firewall. Click Firewall Options. Good: you see the app list—add the app. Bad: Options is grayed out or locked—contact IT.

Yes No (locked)

You can change your answer later.

Is the app in the list with Allow?

Add the app with the plus button if missing. Set to Allow incoming connections.

Click the plus (+) button, browse to the app in Applications, add it. Set to Allow incoming connections. Restart the app and test. Good: app connects. Bad: still fails—check stealth mode or third-party firewall.

Yes No

You can change your answer later.

Is stealth mode on?

Stealth mode can block some traffic. Try turning it off.

In Firewall Options, uncheck "Enable stealth mode" if present. Test the app again. Good: app connects. Bad: still fails—check third-party firewall or contact IT.

Yes No

You can change your answer later.

Contact IT

On a managed Mac, IT must allow the app via policy. Provide the app name and that firewall settings are locked.

Done

Done

The app is allowed and connects. No further action.

Done

Reviewed by Blackbox Atlas

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