I would like to inform you that there is a general ASP.NET AJAX Extensions issue, concerning the new iOS 8 and OS X Safari 7.1 and 8 versions. It is affecting sites using ASP.NET 3.5. Basically, the new Safari version is not properly recognized by the AJAX framework as a browser that supports partial rendering, which breaks the AJAX technology.
In order to fix this issue, you need to edit your browser definition files so that the latest Safari is properly recognized. You can find more detailed information about the issue as well as a workaround for it in the following stackoverflow thread.
The above scenario is the most probable reason for the behavior observed and this tip should help you solve the issue faced.
If you are not using ASP.NET 3.5, could you elaborate a little more on the issue - what is your scenario, expected and actual behavior, are you using Safari or Chrome on iOS 8 and what is the exact version of iOS 8 (8.0.1, 8.1.1, 8.1.2)?
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