Some Samsung phones are showing green lines on the display — what you need to know

Green line appearing on Galaxy S21 phones
(Image credit: @Arjuncr96 / @Hercules_UTD via X)

Users are finding a green line appearing on their Samsung phone screens after a recent update. According to reports, the fault primarily affects the Samsung Galaxy S21 series, including the Galaxy S21 Ultra and the Galaxy S21 FE

Several posts on X allege that the fault arose on the older Samsung phones after updating the device. You can see two examples of this below.

Two devices showing off the green line fault

(Image credit: L: @Entroprox on X R:@Babu__R on X)

Samsung has dealt with several issues recently with a few of its older devices. For instance,  there were recently several reports of the hinge breaking on the Galaxy Z Fold 4. The issue appeared to be that the glue holding the small brushes placed inside the hinge was wearing down, thus blocking the hinge from closing properly.

It isn't only older models that caught Samsung on the back foot. Recently the company had to respond to a reported Mura effect occurring on the Galaxy S24 series that caused a grainy texture at certain brightnesses. This issue is essentially down to the individual pixels on the screen varying in brightness, meaning the color no longer looks uniform and small darker areas start to appear.

What could be causing it?

The fact that the issue appeared after a One UI update suggests that it's the cause of the line, and hopefully means a patch or following update will be able to fix it. But a green line on the screen is often the symptom of a hardware issue than a software one.

These are typically caused by a faulty flux cable connection, which can happen over time. When this cable is damaged or wears down, it causes lines to appear on the screen. 

The idea of an update causing such a hardware fault is unlikely, although there is one possibility. If the update caused increased heat generation in a phone's circuitry, then that coupled with specific environmental factors or heavy usage could loosen the glue holding the display components together and cause damage to the display cable.

This is purely speculation for now though. We have reached out to Samsung for comment and will update you as soon as we hear anything.

It is unlikely that this is solely down to the latest update and is more than likely due to a combination of issues. However, it might be best to avoid updating your older phones for the time being, or to at least do so in a cool and well-ventilated area. Or if you're due for an upgrade, you can take a look at the best Samsung phones to see what the latest Galaxy phones are capable of.

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Staff Writer

Josh is a staff writer for Tom's Guide and is based in the UK. He has worked for several publications but now works primarily on mobile phones. Outside of phones, he has a passion for video games, novels, and Warhammer.