I had the same problem accessing a Webmap and its online Presentation on a variety of different iPads. After turning off halos, I am able now to use the webmap with no visible problems BUT the presentation is still getting me the same error message "A problem occurred with this webpage so it was reloaded." Technical support from ESRI informed me about the following bug found: [BUG-000093906: Web maps that display a hosted feature service including numerous labels with halos are unable to load in iOS devices, and instead, reloads with the error, "A problem occurred with this webpage so it was reloaded."]. The bug has been added to development plans in a future release, I was told. UPD. After turning off halos, re-saving the webmap, freeing cache and browser history, rebooting the ipads, the Presentation is now working as well!
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