IOS App iTunes Connect Screenshots Dimension

When I tried to update the screenshots for my apps in Apple App Store, I get some message as following :

Screenshots must be in the JPG or PNG format, and in the RGB color space. App previews must be in the M4V, MP4, or MOV format and can’t exceed 500 MB.

and when the size is not correct, it simply reports the error, reject the image file and  never say a word about which size it is expected, and I have to figure it out myself.

IOS App iTunes Connect Screenshots Requirement

Format : JPG, PNG (GIF is not included here)

Color Space : RGB (red, green blue)

Dimension :

3.5 Inch iPhone & iPhone 3 640 x 960 px
4 Inch iPhone 4+5 640 x 1136 px
4.7 Inch iPhone 6 750 x 1334 px
5.5 Inch iPhone 6 Plus 1242 x 2208 px
9.7 + 7.9 Inch iPad 2048 x 1536 px
12.9 Inch iPad Pro 2732 x 2048

Reference is here : https://developer.apple.com/library/ios/documentation/LanguagesUtilities/Conceptual/iTunesConnect_Guide/Appendices/Properties.html