1. Use the free tool Image Optim which will not only optimize your png images but should also help overcome this Xcode bug.
I used the tool with the file resubmitted the app. But again the same error but for a different file. That’s good because using Image Optim with the png fixed the issue at least for this file. Next step, use the tool with the file that is supposed to be corrupt this time. Resubmit, and voila everything went fine and the app is waiting for review. And as a positive side effect both of my images have now 25% less size.
To make sure that my images didn’t loose too much in quality I opened the original side by side with the image passed through Image Optim. I didn’t notice any quality loss. I’m no expert but it seems that the too images are identical at least to the naked eye.
And because I’m a skeptic I tried another png from my file for which I didn’t get an corrupt message from iTunes Connect. I was surprised to find out the Image Optim could’t apply any optimization to this png. I think thats a good thing.
So I can say that solution 1 worked for me.
2. Disable PNG Compression in Xcode.
I had found this same solution for the warning: icon dimensions (0 x 0) don’t meet the size requirements bug. I didn’t use it then I didn’t want to use it now.
It might increase the size of your app which in my opinion you do not want.
I read that it worked for some people. Some people also said that it decreased the size of their app, which I find strange.
I can’t say for sure if it works but if solution 1 doesn’t work for you, you can try this.
This solution seems to work too and also as an positive side effect it will reduce the app size (very strange side effect if you think about it. Maybe Xcode messes up the PNG compression.)
3. Change the type of the image from PNG to Icon in Xcode
I read about this in the Apple developer forums. I don’t know if it works. And find it a little bit risky. Do you really want to change the type of an image from PNG to Icon? I don’t know if it will cause some kind of other issues.
So I leave this as your last resort if nothing else works for you.
Original credit of this info goes to Andreas Zimnas