197010 2019-04-17 07:18:07 -0700 Safari doesn't preconnect to origin when using rel="preconnect dns-prefetch" 2026-03-30 01:01:16 -0700 1 1 1 Unclassified WebKit Page Loading Safari Technology Preview Mac macOS 10.14 NEW InRadar P2 Normal --- 1 ad webkit-unassigned ad ap beidson cdumez dmdabbs koivisto paulirish rik webkit-bug-importer yoav youennf oldest_to_newest 1528082 0 367623 ad 2019-04-17 07:18:07 -0700 Created attachment 367623 Test page with preconnect and dns-prefetch Safari doesn't preconnect to an origin if both the preconnect and dns-prefetch hints are included in the same rel attribute e.g. <link rel="preconnect dns-prefetch" href="https://www.wikipedia.org/"> I've used this pattern in the past as a graceful degradation for browsers that didn't support preconnect Tests both using WebPageTest and Safari Inspector using the two attached pages - when the preconnect is successfully made a message appears in the Inspector Console Work around is to specify the resource hints separately 1528083 1 367624 ad 2019-04-17 07:18:45 -0700 Created attachment 367624 Test page with just preconnect resource hint 1528089 2 ad 2019-04-17 07:32:46 -0700 Should have also mentioned that this pattern works in Chrome 1528485 3 ap 2019-04-18 09:54:42 -0700 Looking at the code, it looks like we don't support multiple values in "rel" at all. We do seem to support multiple rel attributes though. Andy, can you try 'rel="preconnect" rel="dns-prefetch"'? 1528486 4 webkit-bug-importer 2019-04-18 09:54:59 -0700 <rdar://problem/50018906> 1528557 5 367746 ad 2019-04-18 13:44:33 -0700 Created attachment 367746 Single link element with rel=preconnect and then rel=dns-prefetch 1528561 6 367747 ad 2019-04-18 13:45:15 -0700 Created attachment 367747 Single link element with rel=dns-prefetch and then rel=preconnect 1528568 7 ad 2019-04-18 13:51:17 -0700 Two new test pages attached where the link element has multiple rel attributes <link rel="dns-prefetch" rel="preconnect" href="https://www.wikipedia.org/"> <link rel="preconnect" rel="dns-prefetch" href="https://www.wikipedia.org/"> In the case where the preconnect rel attribute comes first then Safari preconnects - get message in the console to indicate it, and the WebPageTest waterfall is missing the connection setup (which is normal for Safari when it preconnects) dns-prefetch then preconnect - https://www.webpagetest.org/result/190418_WQ_58c2423b8532c6e12e73677b22a2cffe/ preconnect then dns-prefetch https://www.webpagetest.org/result/190418_15_a09ce74e9616ee5555cc5faaba33cb3c/ For comparison Chrome preconnects in both test cases (preconnect in Firefox appears broken ATM) https://www.webpagetest.org/result/190418_8B_09a0743914357f1ada40740a43065085/ https://www.webpagetest.org/result/190418_XT_62b65003d8ea2a6db70a110aaa84e51f/ 1556192 8 dmdabbs 2019-07-26 11:58:20 -0700 Resource Hints can also be signaled by HTTP headers with multiple rel types. Is that properly supported as well? 367623 2019-04-17 07:18:07 -0700 2019-04-17 07:18:07 -0700 Test page with preconnect and dns-prefetch preconnect-and-dns-prefetch.html text/html 693 ad PCFET0NUWVBFIGh0bWw+CjxodG1sPgogICAgPGhlYWQ+CiAgICAgICAgPG1ldGEgY2hhcnNldD0i VVRGLTgiPgogICAgICAgIDx0aXRsZT5yZWw9cHJlY29ubmVjdCAmIGRucy1wcmVmZXRjaCBkZW1v PC90aXRsZT4KICAgICAgICA8bGluayByZWw9InByZWNvbm5lY3QgZG5zLXByZWZldGNoIiBocmVm PSJodHRwczovL3d3dy53aWtpcGVkaWEub3JnLyI+CiAgICAgICAgPHN0eWxlPgogICAgICAgICAg ICBpbWcgewogICAgICAgICAgICAgICAgd2lkdGg6IDI1MHB4OwogICAgICAgICAgICAgICAgaGVp Z2h0OiAyNTBweAogICAgICAgICAgICB9CiAgICAgICAgPC9zdHlsZT4KICA8L2hlYWQ+CiAgPGJv ZHk+CiAgICAgICAgPCEtLSBsYXJnZSBzY3JpcHQgdG8gYmxvY2sgcGFyc2VyIC0tPgogICAgICAg IDxzY3JpcHQgc3JjPSJqcy9sYXJnZS1zY3JpcHQuanMiPjwvc2NyaXB0PgoKICAgICAgICA8IS0t IGRvYy53cml0ZSBpbiBpbWFnZXMsIGRvbid0IGRvIHRoaXMgYXQgaG9tZSBmb2xrcyEhISAtLT4K ICAgICAgICA8c2NyaXB0PgogICAgICAgICAgICBkb2N1bWVudC53cml0ZSgnPGltZyBzcmM9Imh0 dHBzOi8vd3d3Lndpa2lwZWRpYS5vcmcvcG9ydGFsL3dpa2lwZWRpYS5vcmcvYXNzZXRzL2ltZy9X aWtpcGVkaWEtbG9nby12MkAyeC5wbmciIC8+Jyk7CiAgICAgICAgPC9zY3JpcHQ+CiAgPC9ib2R5 Pgo8L2h0bWw+ 367624 2019-04-17 07:18:45 -0700 2019-04-17 07:18:45 -0700 Test page with just preconnect resource hint preconnect.html text/html 665 ad PCFET0NUWVBFIGh0bWw+CjxodG1sPgogICAgPGhlYWQ+CiAgICAgICAgPG1ldGEgY2hhcnNldD0i VVRGLTgiPgogICAgICAgIDx0aXRsZT5yZWw9cHJlY29ubmVjdCBkZW1vPC90aXRsZT4KICAgICAg ICA8bGluayByZWw9InByZWNvbm5lY3QiIGhyZWY9Imh0dHBzOi8vd3d3Lndpa2lwZWRpYS5vcmcv Ij4KICAgICAgICA8c3R5bGU+CiAgICAgICAgICAgIGltZyB7CiAgICAgICAgICAgICAgICB3aWR0 aDogMjUwcHg7CiAgICAgICAgICAgICAgICBoZWlnaHQ6IDI1MHB4CiAgICAgICAgICAgIH0KICAg ICAgICA8L3N0eWxlPgogIDwvaGVhZD4KICA8Ym9keT4KICAgICAgICA8IS0tIGxhcmdlIHNjcmlw dCB0byBibG9jayBwYXJzZXIgLS0+CiAgICAgICAgPHNjcmlwdCBzcmM9ImpzL2xhcmdlLXNjcmlw dC5qcyI+PC9zY3JpcHQ+CgogICAgICAgIDwhLS0gZG9jLndyaXRlIGluIGltYWdlcywgZG9uJ3Qg ZG8gdGhpcyBhdCBob21lIGZvbGtzISEhIC0tPgogICAgICAgIDxzY3JpcHQ+CiAgICAgICAgICAg IGRvY3VtZW50LndyaXRlKCc8aW1nIHNyYz0iaHR0cHM6Ly93d3cud2lraXBlZGlhLm9yZy9wb3J0 YWwvd2lraXBlZGlhLm9yZy9hc3NldHMvaW1nL1dpa2lwZWRpYS1sb2dvLXYyQDJ4LnBuZyIgLz4n KTsKICAgICAgICA8L3NjcmlwdD4KICA8L2JvZHk+CjwvaHRtbD4= 367746 2019-04-18 13:44:33 -0700 2019-04-18 13:44:33 -0700 Single link element with rel=preconnect and then rel=dns-prefetch preconnect-and-dns-prefetch-seperate-rels.html text/html 699 ad PCFET0NUWVBFIGh0bWw+CjxodG1sPgogICAgPGhlYWQ+CiAgICAgICAgPG1ldGEgY2hhcnNldD0i VVRGLTgiPgogICAgICAgIDx0aXRsZT5yZWw9cHJlY29ubmVjdCAmIGRucy1wcmVmZXRjaCBkZW1v PC90aXRsZT4KICAgICAgICA8bGluayByZWw9InByZWNvbm5lY3QiIHJlbD0iZG5zLXByZWZldGNo IiBocmVmPSJodHRwczovL3d3dy53aWtpcGVkaWEub3JnLyI+CiAgICAgICAgPHN0eWxlPgogICAg ICAgICAgICBpbWcgewogICAgICAgICAgICAgICAgd2lkdGg6IDI1MHB4OwogICAgICAgICAgICAg ICAgaGVpZ2h0OiAyNTBweAogICAgICAgICAgICB9CiAgICAgICAgPC9zdHlsZT4KICA8L2hlYWQ+ CiAgPGJvZHk+CiAgICAgICAgPCEtLSBsYXJnZSBzY3JpcHQgdG8gYmxvY2sgcGFyc2VyIC0tPgog ICAgICAgIDxzY3JpcHQgc3JjPSJqcy9sYXJnZS1zY3JpcHQuanMiPjwvc2NyaXB0PgoKICAgICAg ICA8IS0tIGRvYy53cml0ZSBpbiBpbWFnZXMsIGRvbid0IGRvIHRoaXMgYXQgaG9tZSBmb2xrcyEh ISAtLT4KICAgICAgICA8c2NyaXB0PgogICAgICAgICAgICBkb2N1bWVudC53cml0ZSgnPGltZyBz cmM9Imh0dHBzOi8vd3d3Lndpa2lwZWRpYS5vcmcvcG9ydGFsL3dpa2lwZWRpYS5vcmcvYXNzZXRz L2ltZy9XaWtpcGVkaWEtbG9nby12MkAyeC5wbmciIC8+Jyk7CiAgICAgICAgPC9zY3JpcHQ+CiAg PC9ib2R5Pgo8L2h0bWw+ 367747 2019-04-18 13:45:15 -0700 2019-04-18 13:45:15 -0700 Single link element with rel=dns-prefetch and then rel=preconnect dns-prefetch-and-preconnect-separate-rels.html text/html 699 ad PCFET0NUWVBFIGh0bWw+CjxodG1sPgogICAgPGhlYWQ+CiAgICAgICAgPG1ldGEgY2hhcnNldD0i VVRGLTgiPgogICAgICAgIDx0aXRsZT5yZWw9cHJlY29ubmVjdCAmIGRucy1wcmVmZXRjaCBkZW1v PC90aXRsZT4KICAgICAgICA8bGluayByZWw9ImRucy1wcmVmZXRjaCIgcmVsPSJwcmVjb25uZWN0 IiBocmVmPSJodHRwczovL3d3dy53aWtpcGVkaWEub3JnLyI+CiAgICAgICAgPHN0eWxlPgogICAg ICAgICAgICBpbWcgewogICAgICAgICAgICAgICAgd2lkdGg6IDI1MHB4OwogICAgICAgICAgICAg ICAgaGVpZ2h0OiAyNTBweAogICAgICAgICAgICB9CiAgICAgICAgPC9zdHlsZT4KICA8L2hlYWQ+ CiAgPGJvZHk+CiAgICAgICAgPCEtLSBsYXJnZSBzY3JpcHQgdG8gYmxvY2sgcGFyc2VyIC0tPgog ICAgICAgIDxzY3JpcHQgc3JjPSJqcy9sYXJnZS1zY3JpcHQuanMiPjwvc2NyaXB0PgoKICAgICAg ICA8IS0tIGRvYy53cml0ZSBpbiBpbWFnZXMsIGRvbid0IGRvIHRoaXMgYXQgaG9tZSBmb2xrcyEh ISAtLT4KICAgICAgICA8c2NyaXB0PgogICAgICAgICAgICBkb2N1bWVudC53cml0ZSgnPGltZyBz cmM9Imh0dHBzOi8vd3d3Lndpa2lwZWRpYS5vcmcvcG9ydGFsL3dpa2lwZWRpYS5vcmcvYXNzZXRz L2ltZy9XaWtpcGVkaWEtbG9nby12MkAyeC5wbmciIC8+Jyk7CiAgICAgICAgPC9zY3JpcHQ+CiAg PC9ib2R5Pgo8L2h0bWw+