Disabling browser caching for all browsers from ASP NET

Question

I m after a definitive reference to what ASP NET code is required to disabled browsers from caching the page  There are many ways to affect the HTTP headers and meta tags and I get the impression different settings are required to get different browsers to behave correctly  It would be really great to get a reference bit of code commented to indicate which works for all browsers and which is required for particular browser  including versions   There is a huge amount of information about this issue there but I have yet to find a good reference that describes the benefits of each method and whether a particular technique has been superseded by a higher level API   I m particularly interested in ASP NET 3 5 SP1 but it would be good to get answers for earlier version as well   This blog entry Two Important Differences between Firefox and IE Caching describes some HTTP protocol behaviour differences   The following sample code illustrates the kind of thing I am interested in  public abstract class NoCacheBasePage   System Web UI Page       protected override void OnInit EventArgs e                base OnInit e            DisableClientCaching               private void DisableClientCaching                    Do any of these result in META tags e g   lt META HTTP-EQUIV  Expire  CONTENT  -1  gt             HTTP Headers or both              Does this only work for IE          Response Cache SetCacheability HttpCacheability NoCache               Is this required for FireFox  Would be good to do this without magic strings             Won t it overwrite the previous setting         Response Headers Add  Cache-Control    no-cache  no-store                Why is it necessary to explicitly call SetExpires  Presume it is still better than calling            Response Headers Add  directly         Response Cache SetExpires DateTime UtcNow AddYears -1

User · Accepted Answer

This is what we use in ASP NET      Stop Caching in IE Response Cache SetCacheability System Web HttpCacheability NoCache       Stop Caching in Firefox Response Cache SetNoStore      It stops caching in Firefox and IE  but we haven t tried other browsers  The following response headers are added by these statements   Cache-Control  no-cache  no-store Pragma  no-cache

User · Answer

I m going to test adding the no-store tag to our site to see if this makes a difference to browser caching  Chrome has sometimes been caching the pages    I also found this article very useful on documentation on how and why caching works and will look at ETag s next if the no-store is not reliable   http   www mnot net cache docs   http   en wikipedia org wiki HTTP ETag

User · Answer

There are two approaches that I know of   The first is to tell the browser not to cache the page   Setting the Response to no cache takes care of that  however as you suspect the browser will often ignore this directive   The other approach is to set the date time of your response to a point in the future   I believe all browsers will correct this to the current time when they add the page to the cache  but it will show the page as newer when the comparison is made   I believe there may be some cases where a comparison is not made   I am not sure of the details and they change with each new browser release  Final note I have had better luck with pages that  refresh  themselves  another response directive    The refresh seems less likely to come from the cache    Hope that helps

User · Answer

For what it s worth  I just had to handle this in my ASP NET MVC 3 application  Here is the code block I used in the Global asax file to handle this for all requests       protected void Application BeginRequest                   NOTE  Stopping IE from being a caching whore         HttpContext Current Response Cache SetAllowResponseInBrowserHistory false           HttpContext Current Response Cache SetCacheability HttpCacheability NoCache           HttpContext Current Response Cache SetNoStore            Response Cache SetExpires DateTime Now           Response Cache SetValidUntilExpires true

User · Answer

I ve tried various combinations and had them fail in FireFox   It has been a while so the answer above may work fine or I may have missed something   What has always worked for me is to add the following to the head of each page  or the template  Master Page in  net     lt script language  javascript  type  text javascript  gt      window onbeforeunload   function                    This function does nothing   It won t spawn a confirmation dialog               But it will ensure that the page is not cached by the browser           lt  script gt    This has disabled all caching in all browsers for me without fail

User · Answer

See also How to prevent google chrome from caching my inputs  esp hidden ones when user click back  without which Chrome might reload but preserve the previous content of  lt input gt  elements -- in other words  use autocomplete  off

[asp.net] Disabling browser caching for all browsers from ASP.NET

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