A Web application of mine has begun failing suddenly. My XMLHttpRequest's responseXML is null in Safari on iOS, even though the desktop and Windows Phone browsers I tested could parse the XML and get a non-null responseXML. After lots of guessing and checking tonight, I discovered iOS's responseXML is null when responseText's length is greater than 10000000 (10 million characters). I am testing on iOS 9.0.2 with an iPad 2.
Does anyone know how to exceed this 10000000-character limit? I can't find any documentation about this quirk. Thank you.