When you have connected your Macbook pro to a second monitor for a better visual experience it might occur that the screen may not display the image or the ongoing action on the desktop properly. It might happen that the screen might occur blank or some fluctuations may occur on the screen. This problem occurs due to various reasons.

This article highlights the reasons for such mishaps with the display of the second monitor:

MacBook Pro Not Detecting External Display

First of all check how many displays your MacBook Pro can support as external monitors. For checking this up follow up with some simple steps:

  • Go on to the Tech Specs page of Macbook Pro to get the data about how many external displays the system can have.
  • You need to go on to the Apple Menu. 
  • Then march on to the option “About this Mac”.
  • Then copy out the serial number of your MacBook Pro using double-click and Ctrl+C.
  • Then, move on to the Tech Specs page.
  • Click on the Search Tech Specs bar.
  • Press Ctrl+V.
  • Your serial number will be copied onto the search bar.
  • Press the search button.
  • Now click on the Specs page for your MacBook Pro and it will show up the number of displays your MacBook can support under the Video Support or Graphics option.

Check for the connection between your MacBook Pro and the second monitor. If you find the connection to be a little loose then disconnect the wires and then reconnect them. Make sure that the Thunderbolt or the USB port is only used for making the connections.

Sometimes it may happen that the screen may appear blurry or the display is very much fluctuating. For this issue first, you need to adjust the resolution of your display. For this follow up the steps given below:

  • Choose the Apple menu.
  • Then proceed on to the System Preferences option.
  • Click on Displays.
  • In Display settings, you will see the external display settings in the sidebar of the screen.
  • Click on the scale to adjust the resolution.
  • Select a new and optimal resolution for your screen.
  • Click on Done.

You can also check our recommendations on the best monitor for MacBook Pro.

Frequently Asked Questions (FAQs)

Why is my Mac not connecting to my monitor?

Check for the display adapter used for making the connection. There might be a loose connection between the two, the monitor and the Mac system.

How do I reset my Thunderbolt Port?

Take on the wire connected to the thunderbolt Port. Then take that wire out and hold on for 2-3 seconds. Then you might plug in the wire again in the thunderbolt port. Then you might reset the system also for further corrections.


So, you need to check the connections, resolution, and number of displays supported by your system. For this follow up some simple steps very carefully and with patience. The reason might also be some fluctuations in the brightness level of your system. This might be rectified by some simple settings and some simple contrasts.

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