See the accepted answer https://forums.developer.apple.com/thread/60919
You can save 16-bit assets as 8-bit ones with Preview.app
How to resolve “ERROR ITMS-90682: Invalid Bundle – The asset catalog at ‘Payload/XXXXX/Assets.car’ can’t contain 16-bit or P3 assets if the app supports iOS 8 or earlier.”
With Xcode 8 GM, this error will occur if you include 16-bit or P3 assets in an app submission targeting iOS releases earlier then iOS 9.3. If your app requires wide color functionality you must change your Deployment Target to iOS 9.3 or later. If your app does not require wide color functionality and you wish to deploy it to older iOS versions then you should replace all 16-bit or P3 assets with 8-bit sRGB assets. You can find 16-bit or P3 assets by running “assetutil” on the asset catalog named in the error message from iTunes Connect. The following steps outline the process:
- Create an Inspectable .ipa file. In the Xcode Organizer (Xcode->Window->Organizer), select an archive to inspect, click “Export…”, and choose “Export for Enterprise or Ad-Hoc Deployment”. This will create a local copy of the .ipa file for your app.
- Locate that .ipa file and change its the extension to .zip.
- Expand the .zip file. This will produce a Payload folder containing your .app bundle.
- Open a terminal and change the working directory to the top level of your .app bundle cd path/to/Payload/your.app
- Use the find tool to locate Assets.car files in your .app bundle as shown below: find . -name ‘Assets.car’
- Use the assetutil tool to find any 16-bit or P3 assets, in each Assets.car your application has as shown below. :
sudo xcrun --sdk iphoneos assetutil --info /path/to/a/Assets.car > /tmp/Assets.json
- Examine the resulting /tmp/Assets.json and look for any contents containing “DisplayGamut”: “P3” and its associated “Name”. This will be the name of your imageset containing one or more 16-bit or P3 assets.
- Replace those assets with 8-bit / sRGB assets, then rebuild your app.
Update: If your Deployment Target is set to either 8.3 or 8.4 and you have an asset catalog then you will receive this same error message, even if you do not actually have 16-bit or P3 assets. In this case you will either need to lower your Deployment Target to 8.2, or move it up to 9.x.