Fix “Unknown or Invalid JPEG Marker” Error in Photoshop (Mac Quick Tip)

If Photoshop on your Mac refuses to open a .JPEG and gives you the error: “Could not complete your request because an unknown or invalid JPEG marker type is found,” there’s a good chance the file is actually an HEIC image mislabeled as a JPEG, especially if it was taken on an iPhone. In this quick Designer to Fullstack tip, I walk you through two fast ways to fix it: ✅ Method 1: Rename the File Extension If the image preview works in Finder but not in Photoshop, try changing .jpeg to .heic. This often resolves the metadata conflict instantly. ✅ Method 2: Re-Export with Preview Open the “corrupt” JPEG using Preview on your Mac and export it as: HEIC, or a clean JPEG Either option rewrites the metadata so Photoshop can open the file normally. If your Photoshop JPEGs won’t open due to a bad marker type, this quick fix should get you back on track. Full Blog with Steps: https://designertofullstack.com/fixing-the-unknown-or-invalid-jpeg-marker-error-in-photoshop-on-a-mac/ — 🎨 More design + tech tips: Designer to Fullstack helps creative professionals level up with tutorials, workflows, and problem-solving guides. Subscribe for weekly videos! _____________________________________________________________ *JOIN MY EMAIL LIST* Love quick, helpful tutorials? You’ll love the emails too. 💌 https://designertofullstack.com/join-the-list/ *ABOUT ME* Hello, world. I’m *Kelly Barkhurst* —an experienced Mac-based full-stack designer, educator, and entrepreneur passionately blending artistic vision and creativity with deep technical expertise. With a BFA and MFA in Graphic Design and a certificate in Full-Stack Web Development, I’m uniquely positioned to work at this intersection of design and tech. My driving force is creating meaningful solutions and helping clients and students do the same. *What’s Kelly’s superpower?* It’s using design thinking to strategically plan the BIG picture, then diving deep into the technical “weeds” to bring that vision to life—through beautiful visual design, compelling writing, or well-crafted, functional code. *What brought you JOY today? * 👇 Share in the comments below *SOCIALS* https://twitter.com/@designer2fstack https://www.facebook.com/designertofullstack https://www.youtube.com/@UCWk0aZ-yFzCQX5bMLaISrog