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Fixing the “Unknown or Invalid JPEG Marker” Error in Photoshop on a Mac

By Kelly Barkhurst

December 2, 2025

4 Min read

In Print Graphic Design

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If you’ve ever tried to open a JPEG on your Mac and Photoshop threw the error “unknown or invalid JPEG marker type,” you’re not alone. This is a common issue, especially with images taken on an iPhone. The good news is that the fix is quick, simple, and something you can do right in Finder or Preview.

Could not open because an unknown or invalid JPEG marker type is found.

Below is the video walkthrough, followed by the full video transcript and written steps.

Watch the Video

Hello, so today is a quick tip about how if you’re on a Mac, and you have a JPEG with an extension dot JPEG, and you try to open it in Photoshop and you get cannot open because “an unknown or invalid JPEG marker type is found.” Now, if you click when you’re in your finder and you hold down your spacebar, that pops up a preview, and you can see that the image is there but you can’t open it in Photoshop. Now when you’re in view as a list I can see that this image was taken with an iPhone 11 Pro and I’m in a new Photoshop. So the issue is likely that this file is really a .HEIC and it is mislabeled as a JPEG and so it’s getting a conflict. So one thing that you can do is if you suspect that that’s the issue, simply click into your file name and type in each HEIC, use and you can see it changes the preview, now I can double-click it, and it opens as an HEIC. Okay, so that’s definitely one way. Basically the marker, the metadata is screwed up and so you can fix it by just relabeling it the correct file type. Another thing that you can do is you can open with Preview. In Preview you can do File, Nope File >, Export, and you can choose an HEIC here as well. Now you can also do export. However, I think even if you choose JPEG here and we say try, let’s see what happens. Yep, that will work too. So you can also just open the corrupt file in preview and then save as a new JPEG image and you can get it right as a JPEG for you. Alright, so I hope those options work for you and fix the issue of JPEG’s not opening because of the wrong marker in Photoshop, so that JPEG marker type is unknown or invalid. Alright, good luck!

Why Photoshop Can’t Open Some JPEGs

If you can preview the image in Finder but Photoshop refuses to open it, the file is probably mislabeled. iPhones often save photos as HEIC files. When a HEIC is renamed with a .jpeg extension, Photoshop reads the metadata, gets confused, and flags the file as invalid.

Fortunately, there are two straightforward fixes.

Fix 1: Rename the File Extension

Select the image in Finder.
Press the spacebar to confirm that the preview displays correctly.
Click the filename and change .jpeg to .heic.
The preview will update, and you should now be able to open the file in Preview or Photoshop.

This works because the metadata is intact. The file was simply mislabeled.

Fix 2: Re-export the Image Using Preview

If renaming doesn’t solve it, open the file in the Preview app.

Right-click the file and choose Open With > Preview.
Go to File > Export.
Save the file as either an HEIC or a fresh JPEG.

Preview rewrites the metadata correctly, so Photoshop will open the new file without errors.

That’s It

Both methods work because they fix the mismatch between the file type and the metadata. If Photoshop keeps complaining about an “unknown or invalid marker,” it usually means it’s not a real JPEG at all. A quick rename or re-export will bring it back to life.

If this tip helped you, be sure to check out more tutorials on Designer to Fullstack. I share practical fixes and creative workflows for designers, photographers, developers, and anyone who spends their day inside creative tools.

adobe photoshop

About the author

Kelly Barkhurst

Designer to Fullstack is my place to geek out and share tech solutions from my day-to-day as a graphic designer, programmer, and business owner (portfolio). I also write on Arts and Bricks, a parenting blog and decal shop that embraces my family’s love of Art and LEGO bricks!

By Kelly Barkhurst December 2, 2025