App Store Connect Screenshot Upload Errors: Every Fix (2026)
TL;DR. Almost every App Store Connect screenshot upload failure comes from one of four causes: a hidden alpha channel, a non-sRGB color space, a dimension that is wrong by even one pixel, or a batch-upload race condition. The fast fix for the mysterious ones (the red exclamation mark, IMAGE_TOOL_FAILURE) is to re-export as a flat sRGB PNG or JPEG with no transparency, at an exact accepted size, and upload one file at a time. This guide lists every error message, its real cause, and the exact fix.
Last updated: 2026-08-26.
Disclosure. We make ScreenFast, an AI App Store screenshot generator. It is mentioned once, where it genuinely sidesteps these errors by outputting flat correctly-sized files. Every Apple spec here is cited to developer.apple.com; some accepted-dimension numbers vary between Apple's reference page and the device's native resolution, and we flag that.
The four root causes behind almost every error
Before the message-by-message list, internalize this. The App Store Connect screenshot pipeline rejects a file for one of four reasons, and most of the cryptic errors are the same problem wearing different masks:
- Alpha channel / transparency. PNGs exported from design tools often carry a hidden alpha channel. Apple rejects it.
- Wrong color space. Apple wants flat sRGB. CMYK and wide-gamut Display P3 get rejected.
- Wrong dimensions. The pixel size must match an accepted bucket exactly, with zero tolerance.
- Batch-upload race condition. Dragging ten files at once can stall the server-side processing queue.
Fix those four and you have fixed roughly everything below.
The error reference table
| Error / symptom | Real cause | Fix |
|---|---|---|
IMAGE_TOOL_FAILURE (red exclamation on thumbnail) |
Hidden alpha channel, non-RGB color space, or batch race | Re-export flat sRGB, no alpha; upload one at a time |
| "Images can't contain alpha channels or transparencies" | PNG has an alpha channel | Flatten onto an opaque background, re-export |
| "The dimensions of one or more screenshots are wrong" | Size not in an accepted bucket, or wrong device slot | Re-export at an exact accepted size |
| "Color space not supported" | CMYK or Display P3 file | Convert to sRGB |
| "Unsupported file format" | WebP, HEIC, or TIFF | Convert to PNG or JPEG |
| File rejected for size | Over the 10 MB cap | Compress; keep PNGs under ~8 MB |
| "There are still screenshot uploads in progress" | A partial/stalled upload blocks submission | Delete the stuck asset, re-upload, wait for the green check |
| Can't delete or replace a screenshot | Version is read-only (In Review / Pending) | Use Media Manager, or create a new version |
IMAGE_TOOL_FAILURE: the red exclamation mark
This is the most-reported and most-confusing one. The drag-and-drop spinner fills, the thumbnail appears, then a red exclamation mark shows on hover and "Save" never enables. App Store Connect gives you no useful detail.
It is almost always one of the four root causes, most often a hidden alpha channel or a non-sRGB profile. The reliable fix: open the file in Preview, choose File then Export, untick "Alpha", and confirm the color profile is sRGB. Then re-upload.
A widely-shared "convert PNG to JPG" tip also works, but understand why: re-encoding through an editor strips the hidden alpha channel and normalizes the color profile. The format swap is incidental, not the cure. The cure is flattening and sRGB.
This bug has a long tail. Apple Developer Forums thread 648944 has tracked it since June 2020 and it still recurs, so if a clean re-export does not work, the forum-verified workarounds are: rename the local file (append a -1 suffix) before re-uploading, shorten an overly long filename, upload failed images one at a time via "View All Sizes in Media Manager", add a short pause between each action, and try Safari instead of Chrome.
The +1 pixel bug: why a correctly-sized shot still fails
App Store Connect validates against an exact allow-list of dimensions. There is no rounding and no tolerance. A 6.9-inch screenshot at 1320x2868 passes; the same shot at 1320x2867 fails by that one pixel. Simulator-captured shots can still land a pixel off after scaling, which is why "but I captured it on the right device" is not a guarantee.
The accepted iPhone 6.9-inch slot is forgiving in one specific way: it accepts a family of portrait sizes interchangeably (1320x2868, 1290x2796, and 1260x2736) and auto-scales. The 6.5-inch slot accepts 1284x2778 or 1242x2688. One caveat worth flagging: Apple's official reference page and a device's native resolution do not always print the same number for the "6.9-inch" size, so trust the accepted-bucket list, not a single quoted figure, and verify against the current screenshot sizes.
The fix is simply to export at an exact accepted size. If your tool exports at 1x or an odd canvas, that is the bug.
Wrong device slot (the silent dimension error)
A subtle variant: your file is a valid size, but you dropped it into the wrong device slot. 1290x2796 belongs in the 6.9-inch (or 6.7-inch) slot; devs sometimes drag it into the 6.5-inch slot and get a dimension error for a perfectly good file. As of 2024 Apple reduced the requirement to a single iPhone set (one 6.9-inch bucket) plus a single iPad set (13-inch, 2064x2752), so in most cases you only need to fill the 6.9-inch slot and let Apple scale down. Put the file in the right slot first.
Format, color space, and file size
Three quick, unambiguous ones:
- Format. App Store Connect accepts only PNG (.png) and JPEG (.jpg / .jpeg). WebP, HEIC, and TIFF are rejected as "Unsupported file format". Convert before uploading.
- Color space. Flat sRGB only. CMYK and Display P3 trigger "Color space not supported". Convert to sRGB in your editor.
- File size. The hard cap is 10 MB per image, but real-world reliability degrades as you approach it. Keep PNGs under about 8 MB; if a large screenshot keeps failing, compress it.
Stuck uploads and "uploads in progress"
After a partially failed batch, you can hit "There are still screenshot uploads in progress" or "Unable to Add for Review" even though every visible thumbnail looks fine. A stalled or ghost upload is blocking submission.
The fix: delete the stuck or blank-gray asset, re-upload it on its own, and wait for the green checkmark before adding the next. The popular "upload one at a time and wait for the green check" advice is not in Apple's docs, but it works because the underlying problem is a batch-upload race condition in Apple's processing queue. Uploading singly sidesteps it. A stale browser cache can also cause blank-gray thumbnails, so clearing the cache, switching browsers, or disabling a VPN or ad-blocker can help, and it is worth checking Apple's System Status page.
Can't delete or replace a screenshot (read-only fields)
This one is not a bug. Once a version is "Waiting for Review", "In Review", or "Pending Developer Release", the screenshot fields are read-only. The delete button simply is not where you expect.
Two paths: use "View All Sizes in Media Manager", where the delete control does appear, or create a new app version (or use the metadata-only edit window) to get editable fields again. You cannot change live screenshots mid-review without one of these.
A 60-second triage flow
When a screenshot will not upload, run this in order:
- Is the message about the field being locked? You are in review. Use Media Manager or a new version.
- Re-export the file as flat sRGB PNG, no alpha, at an exact accepted size (1290x2796 is the safe iPhone default).
- Confirm you are dropping it into the matching device slot.
- Upload that one file alone and wait for the green check.
- Still stuck? Rename the file, shorten the filename, clear cache, and try Safari.
That sequence clears the overwhelming majority of cases. The walkthrough below shows the actual upload screen.
How to upload your app to the App Store (Xcode & App Store Connect) demonstrates the real ASC upload UI where these errors appear.
One note on ITMS-90xxx alpha codes (icon vs screenshot)
Developers searching "ITMS-90647 alpha channel" often conflate two different things. The ITMS-90xxx alpha-channel codes (like ITMS-90717, "Invalid App Store Icon... can't be transparent nor contain an alpha channel") are icon validation errors raised at Xcode/binary upload, not screenshot errors. A screenshot's alpha problem surfaces in App Store Connect as IMAGE_TOOL_FAILURE or the explicit transparency message instead. If you hit an ITMS-90717-style code, fix your app icon's alpha channel, not your screenshots. (If you need a correctly-sized, alpha-free icon, our free AI app-icon generator outputs the required 1024x1024 master.)
How we tested
This is a synthesis of Apple's official App Store Connect references (the screenshot-specifications and upload pages on developer.apple.com), the long-running Apple Developer Forums thread 648944, and independent troubleshooting guides. Exact error strings are quoted as reported across those sources. We flag two genuine ambiguities honestly: Apple's reference page and a device's native resolution sometimes print different numbers for the "6.9-inch" size (so we trust the accepted-bucket list), and the popular "upload one at a time" advice is community lore that works around a real batch race condition rather than a documented Apple rule. The IMAGE_TOOL_FAILURE bug has been open since 2020. ScreenFast is our own product, named once where it legitimately avoids these errors.
Where a generator avoids the errors entirely
Most of these failures originate in the export step. A tool that outputs the right thing by default removes them. ScreenFast (our product) generates flat PNG screenshots at the 1290x2796 iPhone 6.9-inch master, with no alpha channel and no transparency, which is exactly the accepted iPhone set that App Store Connect auto-scales for smaller devices. That sidesteps the alpha, color-space, format, and dimension errors in one shot. It does not solve the read-only or stuck-upload issues, which are App Store Connect workflow problems, not file problems. See the AI App Store screenshot generator, or if you design by hand, set your canvas correctly with the Figma template guide and avoid the common screenshot mistakes.
FAQ
What does IMAGE_TOOL_FAILURE mean in App Store Connect?
It is App Store Connect failing to process your screenshot, shown as a red exclamation mark on the thumbnail. The cause is almost always a hidden alpha channel, a non-sRGB color space, or a batch-upload race. Re-export as flat sRGB PNG with no transparency and upload one file at a time.
Why does App Store Connect reject a screenshot that is 1 pixel off?
Apple validates against an exact allow-list of dimensions with no tolerance, so 1320x2867 fails where 1320x2868 passes. Export at an exact accepted size; do not rely on a Simulator capture being pixel-perfect after scaling.
Why can't I delete or replace my screenshots?
The version is read-only because it is in review or pending release. Use "View All Sizes in Media Manager", where the delete control appears, or create a new version to get editable fields.
What screenshot formats and color space does Apple accept?
PNG or JPEG only, in flat sRGB, with no alpha channel. WebP, HEIC, TIFF, CMYK, and Display P3 are all rejected. The hard size cap is 10 MB, but keep files under about 8 MB for reliability.
What size should my iPhone screenshots be in 2026?
The safe default is the 6.9-inch master at 1290x2796 (the slot also accepts 1320x2868 and 1260x2736). Apple auto-scales that set for smaller iPhones, so one well-made 6.9-inch set usually covers the listing.
Why does "There are still screenshot uploads in progress" block my submission?
A partial or stalled upload is hanging in the queue. Delete the stuck or blank-gray asset, re-upload it on its own, wait for the green checkmark, and clear your browser cache if blank thumbnails persist.