Trying to connect your Mac to a second screen but nothing shows up? You’re not alone. A common issue for many users is when the Mac is not detecting an external monitor, even though the cable is connected and the display works fine with other devices. Whether it’s an HDMI port not working on MacBook Pro, DisplayPort to HDMI not working on Mac, or mac not recognizing a monitor at all, this can be frustrating—especially when you need that second screen for work or presentations.
Some users also experience:
- HDMI to projector not working on Mac
- HDMI won’t connect to TV from MacBook
- mac HDMI sound not working on TV
- Mac Mini HDMI not working after update
- Detect Displays button not working on macOS
These issues are typically related to display cache corruption, connection errors, or system miscommunication between macOS and your external display. The good news? You can reset the display subsystem using a safe Terminal command—no settings reset or data loss required.
Solution
- Open Terminal
Press Command + Space, type Terminal, and hit Enter. - Copy the command
- Paste into Terminal
Click into the Terminal window and press Command + V or right-click and select “Paste”. - Run the command
Hit Enter, then input your administrator password if prompted.
Note: The password field remains blank while typing—this is normal.
This command forces macOS to reset the display detection system, which can immediately resolve issues like:
– Mac not detecting second monitor
– External display not detected on MacBook Pro
– HDMI not working with TV or projector
– No sound through HDMI on Mac
– macOS not recognizing monitor over DisplayPort or HDMI
Once executed, your Mac should reinitialize all connected external displays, making them visible again in System Settings → Displays. This is one of the fastest and most effective ways to fix external display issues on Mac without the need for adapters, driver installations, or rebooting multiple times.
If the problem happens again, you can safely run the same command to restore display functionality. Whether you’re using a MacBook, Mac Mini, or an iMac, this method is your go-to fix for when Mac HDMI connections fail or your second screen won’t show up.