It's first time using lightroom and i've been getting these lines on almost every photo that i have been editing and searched how to fix that lines but couldn't find anywhere. Also i shoot in raw(.nef) and tried editing .jpg and the lines are still there. The first photo is the final photo and the second one with the green/black lines is the preview in lightroom
It could be a problem with your video card.
Try turning video acceleration off. That may be dreadfully slow, but if the problem goes away, it means you need to replace your video card.
I don't know if Lightroom has the capability of disabling video acceleration, but many other programs (including free, open-source ones) do. darktable comes to mind.
It could be either a problem with the video card or the card's driver or, as stated, with the files themselves - which would point to either camera or the storage drives you use.
If it is the video card, you can test if the problem goes away if you turn off the graphics hardware acceleration in the lightroom settings. The place looks like this (may vary between versions):
Just take all checkmarks away and restart, then see if the problem persists.
To check if it is the files themselves, just send the file to someone else and let them check if the problem also occurs on their side.
If they also have a faulty image, first replace the memory card you use in your camera. These are usually giving up at some point in time and should be the easiest to replace and check.
This error is related to the output of the monitor and graphic card and has nothing to do with Lightroom's options for visual alarms and its overlays in the software. Prepare an export and see if those hashes are still visible in the output image or not, but temporarily install another graphics card on your device as a test (complete) and refer to the same image in Lightroom again, you should not get such an error. see that .
I don't know how you should solve the problem with graphic processor (maybe power issues, or damaged graphic card) or the software (maybe again hardware issues, or one incompatible software module), but
if you want to fix only a specific photo, you can open image in Matlab or any programming application (considering you know how to process digital images), then detect those lines with high difference in R,G,B values, then apply a Median filter with small window size on those lines, and add a jitter (which selects pixels from near area) and again apply a median effect on them to make it better (not fully solving the problem).