Error 304 Http
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be returned if allowed by the client (e.g. your Web browser or our CheckUpDown robot). The client specifies this in the HTTP data stream sent to the Web server e.g.
Html Code 404
via If_Modified_Since headers in the request. Systems that cache or index Web resources (such 400 http as search engines) often use the 304 response to determine if the information they previously gathered for a particular URL is apache error code 304 now out-of-date. Fixing 304 errors - general You should never see this error in your Web browser. It should simply present the Web page from its cache - because it believes the page has not
Server Response 400
changed since it was last cached. If your client is not a Web browser, then it should equally be able to present the page from a cache. If unable to do so, it is not using the If_Modified_Since or related headers correctly. Fixing 304 errors - CheckUpDown You should never see this error at all for the CheckUpDown service. It indicates defective programming by us or the developers of the
Bad Response 400 Bad Request
Web server software. Either we or they are not respecting HTTP protocols completely. The 304 status code should only be returned if we allow it in the HTTP data stream we send to the Web server. Because we keep no records of the actual content of your URL Web page, we specifically disallow the 304 response in the HTTP data stream we send. So if the Web server implements the HTTP protocol properly, it should never send an 304 status code back to us. This response is not what we expect, so we actively report it as an error even though it does not necessarily mean that the Web site is down. Please contact us directly (email preferred) whenever you encounter 304 errors. Only we can resolve them for you. Unfortunately this may take some time, because we have to analyse the underlying HTTP data streams and may have to liaise with your ISP and the vendor of the Web server software to agree the exact source of the error. 304 errors in the HTTP cycle Any client (e.g. your Web browser or our CheckUpDown robot) goes through the following cycle when it communicates with the Web server: Obtain an IP address from the IP name of the s
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Http Error 200
Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 4.7 million programmers, just like you, helping each other. Join http error 401 them; it only takes a minute: Sign up Why am I getting “(304) Not Modified” error on some links when using HttpWebRequest? up vote 18 down vote favorite 7 Any ideas why on some links that I try to http://www.checkupdown.com/status/E304.html access using HttpWebRequest I am getting "The remote server returned an error: (304) Not Modified." in the code? The code I'm using is from Jeff's post here (the page seems to have disappeared, see an archive copy at the Wayback Machine). Note the concept of the code is a simple proxy server, so I'm pointing my browser at this locally running piece of code, which gets my browsers request, and then proxies it on by creating a new HttpWebRequest, http://stackoverflow.com/questions/2603595/why-am-i-getting-304-not-modified-error-on-some-links-when-using-httpwebrequ as you'll see in the code. It works great for most sites/links, but for some this error comes up. You will see one key bit in the code is where it seems to copy the http header settings from the browser request to it's request out to the site, and it copies in the header attributes. Not sure if the issue is something to do with how it mimics this aspect of the request and then what happens as the result comes back? case "If-Modified-Since": request.IfModifiedSince = DateTime.Parse(listenerContext.Request.Headers[key]); break; I get the issue for example from http://en.wikipedia.org/wiki/Main_Page PS. UPDATE HERE Still can't work this out. Basically I can identify 1 link which has an issue, and it seems to work fine, 2nd time it gets the error, 3rd time OK, 4th time gets the error, 5th time OK etc. As if there is some state not getting cleared or something in the code. I've tried to clean up the code a bit using "using" type statements etc. Here's the code. If anyone can spot why every 2nd time I browse to a link like http://newsimg.bbc.co.uk/css/screen/1_0_16/nol/v4/story.css (starting at the 2nd time, not the first) via this proxy code I get the error I'd love to hear. class Program { static void Main(string[] args) { Proxy p = new Proxy(8080); Thread proxythread = new Thread(new ThreadStart(p.Start)); proxythread.Start(); Console.WriteLine("Proxy Started. Press Any Key To Stop..."); Console.ReadKey(); p.Stop();
here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies http://stackoverflow.com/questions/20978189/how-304-not-modified-works of this site About Us Learn more about Stack Overflow the company Business Learn more about hiring developers or posting ads with us Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 4.7 million programmers, just like you, helping each other. Join them; it only takes a minute: http error Sign up How “304 Not Modified” works? up vote 83 down vote favorite 19 How "304 Not Modified" is generated? How does a browser determine whether the response to a http request is 304.? Is it set by the browser or sent from the server? If sent by server, how does server know the data available in cache, also how does it error 304 http set 304 to an image? My Guess, if generated by browser function is_modified() { return get_data_from_cache() === get_data_from_url(); }; function get_data_from_cache() { return some_hash_or_xxx_function(cache_data); } function get_data_from_url() { return some_hash_or_xxx_function(new_data); } function some_hash_or_xxx_function(data) { // do something with data // what is that algorithm.? return result; } console.log(is_modified()); I am relying on 3rd party API provider to get data, parse & push it to DB. The data may or may not change during every request, but the header always sends 200, I do not want to parse, check the last Unique ID in DB & so on.. to determine the change in data, nor compare the result directly rather I md5(), sha1() & crc32() HASHed the result & works fine, but wondering the algorithm to determine 304 I want to use same kind of algorithm to determine the change in data. http browser http-headers firebug http-status-code-304 share|improve this question edited Feb 10 '14 at 17:17 asked Jan 7 '14 at 17:36 VenomVendor 6,84883774 1 Did you Google it? developers.google.com/speed/articles/caching mobify.com/blog/beginners-guide-to-http-cache-headers –SLaks Jan 7 '14 at 17:42 Yes I googled for how 3