Cannot download or open HEIC images in Messages

Re: Cannot download or open HEIC images in Messages

You may want to try looking in the "Shared with You" folder in the Photos app:

Photos from Messages are likely to be there, and open ok in Photos.

Apple support provide this article (link below) with more "share" details.

https://support.apple.com/guide/iphone/iphb66cfeaad/ios

Eg: says:

":Find all the content someone shared with you

1. Go to the Messages app  on your iPhone.
2. Open the conversation whose content you want to see.
3. Tap the contact or group icon at the top of the conversation.
4. Swipe left, then tap Photos, Links, Documents, Locations, or Wallet.
5. If a category doesn’t appear, you didn’t receive anything of that type in this conversation.

Note: Content only appears in Shared with You if the person who sent it is in your contacts.

You can find a Shared with You section in Photos, Safari, Music, Podcasts, and other supported apps.

If you don’t want items someone sends to you to appear in those other apps, tap the contact or group icon at the top of the conversation, tap Info, then turn off Shared with You."

Re: "... cartoons that were originally JPEG files are being converted to .heic files"

Perhaps you (and / or your attachment sender) have a limitation on the image-size that can be sent and received:

"Note: Your carrier may set size limits for attachments; iPhone may compress photo and video attachments when necessary."

above quote comes from:

Take and edit photos or videos in Messages on iPhone:

https://support.apple.com/guide/iphone/iph3d039f23/26/ios/26

We have the option to use the Mail app (or Dropbox etc.) for images with higher resolutions, or larger file-sizes.

Apple's website for feedback / bug-reports / feature requests etc:

https://www.apple.com/feedback/

I assume that the OP is hoping for an answer that will make Messages revert to how it previously handled images: displaying them within the app. Accessing the images via Photos or the multi-step sharing is cumbersome and significantly detracts from immediately seeing and reacting to texted images within a Messages conversation.

In my case cartoons that were originally JPEG files are being converted to .heic files, with the same results as the OP's. The issue is not duplicated on two different Macs that I checked.

This is apparently another iOS 26 bug. I will go elsewhere seeking a confirmation that suspicion and hopefully a fix. . .

Obviously, this is another iOS 26 bug