Missing required icon file (IOS)

Missing required icon file. The bundle does not contain an app icon for iPhone / iPod Touch of exactly '57x57' pixels

Problem:
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I was trying to update my app in Appstore and I have started to receive this failure message. I checked over the internet for any solution, but none of them work. I have not changed my icons so this failure should not appear at all. 

I have checked the plist file, but always the same issue. The bundle is theoretically missing two icons 57x57 and 72x72 sizes.

Renamed icons and setup the whole icons package in the project, still the same issue

Solutions:
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I ran into this same problem using xCode 5 - all the icons are there and appear correctly on the corresponding devices, but the validation fails. After some experimentation, I found that the following steps will resolve the common causes:

1) Ensure the correct filenames are used

The legacy icons need to follow a specific naming scheme (for apps supporting iOS 6.x and lower):

 57 x  57 --> Icon.png        (iPhone)
114 x 114 --> Icon@2x.png     (iPhone Retina)
 72 x  72 --> Icon-72.png     (iPad)
144 x 144 --> Icon-72@2x.png  (iPad Retina)
Note that iPad icons are called Icon-72. Icon~iPad, which worked in the past, doesn’t work any more (at least, not for me - it generates the same error that you reported).

The naming scheme for icons needed in iOS 7 and later is:

120 x 120 --> Icon-60@2x.png  (iPhone Retina)
 76 x  76 --> Icon-76.png     (iPad)
152 x 152 --> Icon-76@2x.png  (iPad Retina)
The easiest way to update the names is to click on them in the file browser in xCode and rename them directly there.

Source of filenames: https://developer.apple.com/library/ios/qa/qa1686/_index.html

2) Check that the Project file has detected all the icons

Click on your project file in xCode, and make sure the App Icons section has picked up each of the files. If not, manually select them. If you cannot select the icon file, it’s likely that the dimensions aren’t correct. You can check this by selecting the file in Finder, and pressing CMD-I to Get Information, and look at the dimensions under More Information.

3) Make sure that the plist has the right info

Click on your ProjectName-Info.plist file, and check the array underCFBundleIcons~ipad/CFBundlePrimaryIcon/CFBundleIconFiles. It should contain 4 entries: Icon-72, Icon-72@2x, and the names of your iOS7 icons. If there are any extra entries (e.g. for the old icon filenames), remove them by pressing the - button. If they stay there, validation will fail when it's unable to find the corresponding files.