macOS Screen Sharing Not Working Fix

What Does This Error Mean?

When macOS Screen Sharing stops working, you cannot remotely view or control another Mac on the same network. Screen Sharing uses the VNC protocol to display one Mac's screen on another. Common causes include the Screen Sharing feature being disabled in system settings, a firewall blocking the connection, network configuration issues, or an Apple ID sign-in requirement that needs to be met.

Affected Models

MacBook Air
MacBook Pro
iMac
Mac Mini
Mac Pro
Mac Studio

Common Causes

Screen Sharing is disabled in the target Mac's System Settings under Sharing
The Mac firewall is blocking incoming Screen Sharing connections on port 5900
Both Macs are not on the same local network or are separated by a VPN
The Apple ID used for iCloud screen sharing is not signed in or is signed in on a different account
The target Mac's display is set to never wake, preventing remote connections from displaying correctly

How to Fix It

Enable Screen Sharing on the target Mac. On the Mac you want to connect to, go to System Settings > General > Sharing. Toggle on 'Screen Sharing.' Note the VNC address shown (e.g., vnc://192.168.1.x).

Screen Sharing is disabled by default. It must be explicitly turned on on the Mac you want to control.
Connect from the other Mac. On the Mac doing the connecting, open Finder, then press Command + K and type the VNC address from Step 1. Click Connect and enter the target Mac's username and password.

Alternatively, open Finder and look under Network in the sidebar. If the target Mac appears there, double-click it and click 'Share Screen.'
Check the firewall settings on the target Mac. Go to System Settings > Network > Firewall. If the firewall is on, click Options and make sure 'Screen Sharing' is listed as allowed.

macOS Firewall sometimes blocks Screen Sharing even when it is enabled in Sharing settings. Both settings need to be configured correctly.
Verify both Macs are on the same network. Open System Settings > Network on both Macs and confirm both are connected to the same Wi-Fi network or router. Screen Sharing only works on the same local network by default.

If the Macs are on different networks, use Apple Remote Desktop or share the screen via iMessage or FaceTime instead.
Restart Screen Sharing service on the target Mac. Open Terminal and type: sudo launchctl stop com.apple.screensharing — wait a moment, then: sudo launchctl start com.apple.screensharing

Restarting the Screen Sharing service clears any crashed state without requiring a full system restart.

When to Call a Professional

Screen Sharing issues are almost always a configuration problem solvable without professional help. If you need access to a remote Mac over the internet (not just local network), consider Apple Remote Desktop or a third-party tool like TeamViewer.

Frequently Asked Questions

Can I use Screen Sharing over the internet (not just local network)?

The built-in macOS Screen Sharing is designed for local networks only. To access a Mac remotely over the internet, you can use Apple Remote Desktop (paid) or enable Back to My Mac via iCloud if available. Free alternatives include TeamViewer, AnyDesk, or Chrome Remote Desktop. Alternatively, set up a VPN to your home network, which makes remote access work through the normal local Screen Sharing feature.

I can see the other Mac under Network in Finder but clicking Share Screen does nothing. Why?

This usually means Screen Sharing is not enabled on the target Mac, or the firewall is blocking the connection silently. Verify that Screen Sharing is toggled on in the target Mac's Sharing settings. Also try connecting by typing the VNC address directly in Finder's Connect to Server (Command + K) — it sometimes bypasses the issue with the Network browser.

What is the default port for macOS Screen Sharing?

macOS Screen Sharing uses VNC on port 5900. If you have any network devices, firewalls, or security software that filter ports, ensure port 5900 is allowed for local network traffic. Some routers block VNC ports by default as a security measure.