22381 2013-06-16 02:29:12 +0000 When the user agent reestablishes or fails the connection it would be useful to have some indication of the reason for failure. Consider that most applications will wish to inform their user of an [...] 2013-07-02 22:33:34 +0000 1 1 1 Unclassified WHATWG HTML unspecified Other other RESOLVED NEEDSINFO http://www.whatwg.org/specs/web-apps/current-work/#top P3 normal Unsorted 1 contributor ian ian mike contributor oldest_to_newest 89364 0 contributor 2013-06-16 02:29:12 +0000 Specification: http://www.w3.org/TR/eventsource/ Multipage: http://www.whatwg.org/C#top Complete: http://www.whatwg.org/c#top Referrer: Comment: When the user agent reestablishes or fails the connection it would be useful to have some indication of the reason for failure. Consider that most applications will wish to inform their user of an error rather than fail silently; if the best possible is "Connection failed for unknown reason" this gives no hints to the user about how to solve the problem. For example the ability to report the difference between a Not Found error and a connection timeout can inform users if they should check their own network connection or contact the site administrator. The fact that the user agent is supposed to attempt to reconnect is not alone sufficient to let an error go unreported. If someone's network cable falls out it can attempt to reestablish forever, but it would be much more effective to prompt the user to plug it back in. While in theory this could be used to gather information about a network, such is already available by making ordinary CORS requests (via XMLHttpRequest etc) Posted from: 108.20.225.179 User agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:21.0) Gecko/20100101 Firefox/21.0 89715 1 ian 2013-06-21 16:23:12 +0000 Actually we don't provide any less information than you can get in other ways, as far as I can tell. We can't, because leaking information about the network would, as you surmise, be a security problem, e.g. exposing intranet topology. I've updated the spec to suggest that debugging info be provided in consoles, but I don't know if that helps your case. Would you like the browser to tell the user what it knows about connection problems as well, somehow?