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 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.
If you are using ASP.NET 3.5 and the problematic devices are running on iOS 8+, this tip would help you solve the issue faced.
And if these conditions do not match your case, could you provide a runnable sample project and steps to reproduce the issue on our side. I would be also very helpful if you specify the Telerik UI for ASP.NET AJAX version used, as well as devices' OS and browsers.
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