Persistent horizontal lines appear on iMac screen

The same thing just happened to my 2021 M1 iMac.

There are consistent gray lines that formed 3 days, at the bottom section of my screen, that make it impossible to read the text behind it. Taking a screenshot reveals its not a softward issue as the screenshots to now show the lines. It's a hardware issue and I'm not sure how to fix it as the comptuer itself is built into the screen. I cannot replace just the screen on an iMac. I'm posting a picture from my phone (since screenshots do not help) - attached

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I'm in Hong Kong too and had exactly the same experience: called support and showed them this thread, support told us to go to Genius Bar, showed this thread to the engineer at Genius bar and they only said they can't offer free replacement that is not in the service program, and told me to get the display replaced at full price or get a second monitor.

Now my screen blacked out completely.

I want to chip in to bring this to Apple's attention, I have the same issue as what other users have mentioned.

• Persistent horizontal that has expanded to cover half the screen.
• Spoke with Apple a couple of times
• Was asked to visit Apple Store for physical diagnostics
• Rejected at the store and rejected repair on the phone

This is clearly not a wear and tear, more like a "latent defect".

Apple needs to know this and do the right thing for their customers.

If they had designed their products to be repairable, this should be a simple replacement of the flex cable.

Had this product been designed to be repairable, I'm sure many users would have chose to buy the flex cable and replace it themselves.

And not having to deal Apple support, which has become unproductive at this stage.

My M1 iMac 24-inch is experiencing a serious display defect: horizontal black lines appear on the screens after about 3 years of use. This appears to be widely documented in Apple Community forums and some tech media. This suggests a systemic design or manufacturing flaw affecting my device which is now out of warranty. I've been a lifelong Mac user, starting with the Classic (b/w) and equipping my sign business with all Macs.

I feel disappointed and somewhat betrayed.

I have had the same issue starting September 28 2025.

I took my M1 iMac into the genius bar and left it for inspection. It has always been in a dry, dust-free environment in my small office without issues. I was told it would be $550 or so for repairs and perhaps another $90 in labor. I can't use my business mac like this, and the use of another monitor has made my eyes worse in the past two weeks. Photos attached.

My experience did not result in an exception to repair for free. I was told that my mac warranty expired too long ago, that there are no extenuating circumstances (like being out of the country when warranty expired) that would allow for an exception, and that there is a 90-day warranty on repairs, but a repair following that would have to be by the grace of the genius bar or 'senior advisor'.

This makes me think that the "acceptable lifetime of an iMac" has gone from almost ten years (for my imac 27") to 3-4 years?

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Adding my voice to this growing choir. The lines appeared last week on my 2021 M1 with Tahoe 26.0.1, and after trying everything I and the online tech support could think of, I was finally advised to take the Mac to Apple for them to check. From where I live/work, this is not a practicable solution considering the likely outcome of "you have to pay for the repairs to change the whole screen assembly".

I'm desperately hoping that enough voices will make Apple consider this a free repair program.

My previous iMac lasted 10 years. I've been owning Macs since the Quadra 610. I know I'm getting old, but clearly "they don't build'em like they used to"... :D

UPDATE: Last week I posted about the black lines on my iMac. I haven't had time to contact Apple yet, but I wanted to leave a comment here to point out something else I discovered.

The black lines on my iMac are all at the very bottom of the screen. I know that one possible cause people have been mentioning is that some internal part is breaking down because of heat overtime. So I started touching the screen to see if I could feel any extra heat, and... OUCH!!! I felt like I burned my finger! Whenever I try to touch the bottom left corner of the screen, it hurts a lot! It feels like EXTREMELY HOT. It goes away after I turn off the screen, but it comes back seconds after turning the display back on.

Has anyone else found the same thing?

I am also in Hong Kong.

been calling and speaking to senior advisor. But always declined free repair they always say they cant do anything.

i told them about this thread and they say everyone case is different. I told them about how some people get repair for free they said it depends in location. I was like in Hong Kong we are one of the top Apple users and this free repair does not apply to us? Probably because they know majority of hong kong people are willing and can afford to pay.

You also from Singapore? me too. My is M3 iMac the lines suddenly appear at the bottom. After using one year +... Really can't accept. I mean We take care our iMac never split any water or whatever just sitting on the table , always dust it the screen etc keep it clean yet this thing happen. My old intel iMac still working ok at least the screen never get lines..is bought at 2015. Now is 2025 the screen no doubt got pinkish hue and burn mark if you happen see live stream for sometime but at least it will gone after few mins. At least the intel iMac justify , we know computer age too become slow etc but really can't accept on M3 iMac , it seem like all M series will have line issues after using for one year.... So now you still continue using it?

Same for me, M3 iMac user here. The lines appear at the very bottom. I have to drag the browser up a bit as Is very distracted by those lines cover those text further down. Literally can't even see the text while working...

I more concern this lines will spread further as times go by , once reach in the middle You literally can't even use it for work since can't see the text...

In fact for my M3 iMac I notice there is slight dark colour like burn mark on the top casing instead the bottom.

My 2021 iMac 24" M1 is suffering this issue since 1 year ago. As soon as the fault happened I had a phone call to Apple Italy explaining my issue and few hours later I was called back from some "responsible" who told me I had to pay for fixing. Later I left several feedbacks but no reactions, as if they were deaf.

I know this page is not followed by Apple, but where else shall we should write to complains ?

Today morning I simulated to swap my M1 iMac with a new one...and the procedure asked me explicitly if the screen shows lines on it. I don't know if it's a new question (I didn't simulate swapping in the past).

Totally disappointed

Giorgio

Sad to say Even they offer free repair on the screen, the lines problem will still come back upon using it for one year or so. FYI My is M3 iMac also encounter this flaws beside your M1. In fact I curious on those using M4. I don't feel shock their iMac after using it for one year or so , Lines suddenly appear on their screen. IF that happen means Apple Quality is indeed in Doubt since the flaws start from M1 now continue to M3....

I took another poster's suggestion to write to Tim Cook. I received a reply within a couple of hours from 'Brandi', a rep at Apple. I replied to the email restating my case and received a call today after I missed a VM. I spoke, pleaded, actually, stating my case (and those of the 740+ unique individuals who have posted in this forum or clicked "me too", asking for Apple to take responsibility for their problem causing the damaged screen. I was on the phone for about 24 minutes without result. She said she would set up a (another) call with a senior advisor and advocate for me.

To keep this short, I'm rethinking my 'blind' loyalty to Apple since becoming a customer with the Mac Classic in the early 1990s. I'd like to have a reason to remain a loyal user.

I am very disappointed with Apple for two reasons:

1. My 2021 iMac screen started displaying horizontal lines (and flashing) on the bottom half of the screen. Since so many others have also reported this problem, it speaks directly to the deficiency in this Apple product.
2. I traded it in for a Mac Mini last week. The trade-in value was estimated at $45. Today I got an email saying I had misrepresented the product and the new trade-in value was $0.. That is because I accidentally said that my machine had a 256GB SSD when it actually had a 512GB SSD!!!

This is just addding insult to injury. Apple should be ashamed of themselves.

Thanks for all this information which call to Apple Support provided none of when my iMac 2021 suddenly developed flickering horizontal lines on the screen when I turned it back on after shutting it down for a week while I was out of town. I have had it for 4 years sitting on my desk--no damage by me. For what it is worth, I found the "Product Feedback" page on Apple website and sent link to this thread, and wrote this about my defective iMac:

"https://discussions.apple.com/thread/255220596?sortBy=rank

I have joined the hundreds of iMac customers who have been burned by this defect as you will see in above thread. My family own Apple products since the 1980s, both at home and at work, for their quality, reliability and customer accountability. No longer it seems when a 4 year old iMac in pristine condition out of the blue develops flickering horizontal lines on all but the top of the screen. Talk about a headache. Apple's solution: buy a new $600+ screen (same design) with a 90 day warranty! Where is the investigation? Apple acknowledgement/help? The fix? Meanwhile until the hardware glitch is fixed: recalls, free or highly discounted screen/computer replacements. Our loss of $/time/energy/lost productivity is not small."

Only hope is protest of enough customers.