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Prinnnnza
User level: Level 1 (4 points)

iMac (M1, 2021) 24-inch screen shows horizontal flickering lines

Horizontal lines over iMac (M1, 2021) 24-inch screen


Hi, so this problem happened around 10 hours ago. These lines also flickers a lot and looks like this.


Steps taken:

  • Restart the iMac
  • Screen Mirroring (the screen is normal when being mirrored to my Macbook)
  • Screen capture (Normal screen image without black lines)


Posted on Oct 4, 2026 7:28 AM

1 reply

den.thed
User level: Level 10 (99,154 points)

Oct 4, 2026 7:48 AM in response to Prinnnnza

That is a well known issue with the 24" M1 iMac's.


Check the following Community Threads for some other examples and solutions.

Persistent horizontal lines appear on iMac Screen - Apple Community

Screen Failure on 24-inch-iMac, M1, 2021 - Apple Community

Horizontal Lines on Screen of iMac, 24", 2021

iMac 24inch M1 Screen Defect


To contact Apple Support or your local Apple Authorize Service Provider.

Mac - Official Apple Support

Find Locations

Originally posted at discussions.apple.com/thread/256370258