Persistent horizontal lines appear on iMac screen

I got an iMac (24”, M1, 2021) in July 2021 when it first came out, almost 3 years ago. It has been in daily use since; however, last week flickering black horizontal lines suddenly started appearing in the bottom half of the screen.

Even after restarting and updating, the annoying lines keep appearing on the screen, making it unusable. Turned the iMac off for a few days, but the problem persists. Apart from the screen, everything else is working as it should.

It’s very frustrating to use the iMac with these unnoticeable, irritating horizontal lines on the screen. It's such a disappointment to see this issue; without a cause, within such short time.

Whatever be the culprit, once it comes, it'll never go... and will only keep expanding all thru the monitor. Mine keeps juggling between half the screen space and one-fourth. I've already ordered an external monitor as back-up to continue using my iMac M1 model with horizontal lines, as over a period of time u will get EYE STRAIN working on it seeing those horizontal lines flicker all thru the day :(

Hi there,

I'm having the same problem with my iMac. While I'm on a video call, my screen suddenly doesn't look right, like it's covered with a screen. Tried restarting, updating the system, and safe mode to no avail.

I bought it in the UK in September 2021. The specific model is MGPH3B/A. iMac m1 4 ports.

I was originally going to follow the advice of Apple customer service and take it to an Apple store. Thank you everyone for your comments, which saved me a time-consuming and labor-intensive journey. Replacing the screen is really expensive. I'll probably look for any replacement monitors with a similar resolution to the iMac.

Hope to see any updates.

There is no fix. The only solution is to replace the screen. When I bought the imac in June 2021 since it was a new product on the market I made an insurance plan for 5 years that costed me 150€. Last month the store replaced the screen with no additional charges.

This is the exact same thing that’s happening to me right now. I thought it was just from the heat, but oddly enough, after turning my computer on after 2 minutes, the upper right corner is already HEATING UP. But it’s only on that specific corner???

This problem was posted 6 months ago and there is still no solution?

This happened to me yesterday and I thought leaving it a day would solve the issue. Now I am looking for solutions online and the amount of users experiencing this is shocking. I’ve been using my iMac for a little over 2 years as well. What’s happening? Apple, do something.

I have the same problem with a 24inch iMac purchased December 2022, in Athens, Greece. Black horizontal lines filled the screen and the upper right corner of the screen is strangely hot when you touch it. I have not updated macOS, I do not think it is related to that.

Woke up this morning to find I also have this same issue on my iMac. This is not only distressing, but ****** me off as I cannot afford to replace or repair it. I have only had this machine for two years (like everyone else) and it has shown no other issues until today. Interestingly enough, the lines do not show up if I take a screen shot of the display. This is not Steve Jobs' Apple anymore, this company has turned to trash IMNSHO.

nope, if you tried replace it from outside apple service center or another AASP (cheaper price) you will loose true tone feature (on your new display that you replace) it's because need some system configuration from the Apple (it's apple secret) and it will happen and all Apple product (with the display of course), and something you need to consider is, will this happen again in two year after you are replace it?

can you multiple claim on it? what if your new display will malfunction again in two year after you claimed on your first? are you sure i'ts a good one or it's just like your display before (normal display and boom) there you go, it happen again ?

Looks like 90 days to me...

6. Apple warrants for a period of ninety (90) days from the date of service (1) that service will be performed in a competent and workmanlike manner and (2) that all parts used to service your product will be free from defects in materials and workmanship, unless otherwise specified by Apple.

And possibly even get a used part!

5. Apple may use parts or products that are new or previously used Apple genuine parts that have been tested and passed Apple functional requirements

Legal - Repair Terms and Conditions - Apple

Same issue here. iMac M1 2021, pre-ordered it. I've taken the best care of it, after all, it's just sitting on a desk. Seems like the display just spontaneously failed. This happened a week ago.

I don't know if I should replace the screen, because what if it happens again? I'm afraid it's the problem with the design of the screen and/or the computer itself, therefore a replacement may not completely fix the issue in the future.

Can we please get a response from Apple? This doesn't seem like it's an isolated issue, as evident from this thread. A lot of people are having this same problem. This makes me think it's a problem with the design or the manufacturing process.

I am now communicating with a senior advisor from Apple (Katerine) she sounds very professional and empathic and she acknowledges that something strange is taking place with so many cases.

I am forwarding the pictures and data to file a case and trusting the engineers who will review the case will take responsibility and hopefully this will be resolved not just for me but for all of us, please keep all your evidence posted here so they can see the pictures.

Same situation as well, bought mine in September 2021 and the lines started to appear in March 2023. At first I thought it was just me but seeing all the responses here, this is clearly not an isolated issue.

Was putting off sending it for repair since I was hoping the display will go back to normal by itself over time, since the lines tend to flicker and on some days they take up less of the screen.

However in April 2024, it got so much worse with the lines completely taking up the display, rendering it impossible for me to navigate or even use the computer itself.

Would like to ask if there’s a recommended adaptor or cable to connect my M1 iMac to an external HDMI display so I could access and back up my files? Much appreciated!

I have an iMac, bought in 2021. It has been perfect until today. Totally out of blue, flashing horizontal lines appeared in the screen. After a while, the lines "stabilized" and reduced to a single line (see in the attached photo). Apple, please help bring my iMac to normal. Thanks!