RESOLVED INVALID 173719
Response.flush over HTTP/2 causes white page 
https://bugs.webkit.org/show_bug.cgi?id=173719
Summary Response.flush over HTTP/2 causes white page
brett.postin
Reported 2017-06-22 09:22:46 PDT
Problem In a version of Safari that supports HTTP/2 (i.e. v9+) running on macOS “El Capitan” v10.11 or newer, when accessing a webpage served from IIS10 via HTTP/2 (e.g. Windows Server 2016 / Windows 10), if the page contains a "Response.Flush" then it will not load. It simply hangs with a white screen. Web server CPU usage also spikes during these occurrences. Cause The cause of the issue is using Response.Flush. I have only confirmed this in Classic ASP so I do not know about .NET, but removing those lines makes the pages load fine. This thread (https://forums.iis.net/t/1235574.aspx?Response+Flush+not+working+on+SSL+site+in+classic+ASP) suggests that when Response.Flush is used, IIS switches protocol from HTTP/2 back to HTTP/1.1. Safari cannot handle this, whilst all other browsers seemingly can. Demos from the link above: Working - http://limoeventplanner.com/safari-test.asp Not working - https://limoeventplanner.com/safari-test.asp
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Radar WebKit Bug Importer
Comment 1 2017-06-22 23:32:39 PDT
<rdar://problem/32942239>
Alexey Proskuryakov
Comment 2 2017-06-29 01:22:45 PDT
This is not an issue in WebKit, but in underlying system frameworks, so marking as INVALID. Can you still reproduce with macOS High Sierra beta?
brett.postin
Comment 3 2017-06-29 02:01:21 PDT
I will try to get access to High Sierra to test. Do you have any more details or can you redirect me elsewhere to follow this up? Our app is rendered virtually useless in Safari over http2.
brett.postin
Comment 4 2017-07-31 04:50:16 PDT
I can confirm that the "Not working" link above seemingly works in Safari 11 running on High Sierra beta.
Brady Eidson
Comment 5 2017-07-31 11:14:20 PDT
(In reply to brett.postin from comment #4) > I can confirm that the "Not working" link above seemingly works in Safari 11 > running on High Sierra beta. That's good news. (In reply to brett.postin from comment #3)> > Do you have any more details or can you redirect me elsewhere to follow this > up? Since networking is handled by system components on Mac/iOS (NSURLSession and many others) the correct place to report bugs for such issues is http://bugreport.apple.com
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