Why Discord, Slack & Teams Won’t Preview Your iPhone Photos (Fix Upload Errors)
Updated: January 2026
It kills the vibe of the conversation instantly: You want to share a funny photo on your Discord server, or update your boss on Slack with a picture of your work. You drag the file from your computer into the chat window and hit Enter.
But instead of a nice, large image popping up for everyone to see, the chat app just posts a generic “File Download” icon labeled IMG_5921.HEIC.
Nobody wants to click “Download” just to see a meme or a quick update. In this guide, we will explain why chat apps struggle with iPhone photos and the instant way to make your images visible again.
The Problem: “File” vs. “Image”
Apps like Discord, Slack, and Microsoft Teams are built to be cross-platform. To ensure they run fast on every device, they rely on standard web technologies to generate image previews.
HEIC is not a standard web image. It is a proprietary format owned by Apple.
When you upload a JPG, the app says, “Ah, a picture! Let me display it.”
When you upload an HEIC, the app says, “I don’t know what this is. I’ll just treat it like a generic document.”
PC Users: If your computer can’t even open the file before you upload it, check our guide on Opening HEIC on Windows 10 & 11.
The Solution: Convert for Instant Previews
If you want your friends or coworkers to see your image inline (without clicking anything), you must upload a JPG.
- Go to our Home Page Tool.
- Drag your photo into the conversion box.
- Download the JPG.
- Drag that file into Discord, Slack, or Teams.
Result: The image expands perfectly in the chat window for everyone.
Viewing Mobile Uploads on Desktop
Sometimes, the issue is reversed. Your coworker uploaded a photo from their iPhone, and it looks fine on their screen. But you are sitting at your Windows PC using the Slack desktop app, and you can’t see it.
This is because their phone “previewed” it locally, but your desktop doesn’t have the software to read it. You need to download that file and convert it to view it.
Android Users: If you are on an Android phone trying to view a Discord upload from an iPhone user, read our Android HEIC Guide.
Sharing a Batch of Photos?
If you are dumping 20 photos of a weekend trip into a Discord channel, uploading them as HEIC files is a nightmare. People have to download 20 separate files to see them.
Be a good friend: Batch convert them first.
Use our Unlimited Batch Tool to turn that folder into JPGs. Then, when you upload them, they will appear as a beautiful gallery that people can scroll through instantly.
Is this happening in Outlook too?
If you are having trouble with Slack, you are probably having the exact same trouble with email attachments.
Fix that too: Read our guide on Why Email Attachments Won’t Open.
Chat App FAQ
Why does Discord say “Upload Failed”?
Sometimes, HEIC files are larger than they appear because they contain extra “Live Photo” video data. If you hit the 8MB (Free) or 50MB (Nitro) file limit, the upload fails. Converting to JPG using our tool strips the heavy video data, often reducing the file size enough to upload successfully.
Can Trello preview HEIC files on cards?
Generally, no. If you attach an HEIC to a Trello card, it will not show as the “Card Cover.” You must use a JPG or PNG if you want the image to be visible on your Trello board view.
Does converting lower the quality for my design team?
If you are sending “Reference” photos, our converter is perfect. If you are sending “Final Print-Ready Assets,” you should probably Zip the original files. But for 99% of daily work chat, a high-quality JPG is exactly what you need. (See our HEIC vs JPG Quality Breakdown).