On IE CSS font-face works only when navigating through inner links

Question

Our webdesigner has created a CSS with the following font-face:

@font-face {
    font-family: 'oxygenregular';
    src: url('oxygen-regular-webfont.eot');
    src: url('oxygen-regular-webfont.eot?#iefix') format('embedded-opentype'),
         url('oxygen-regular-webfont.woff') format('woff'),
         url('oxygen-regular-webfont.ttf') format('truetype'),
         url('oxygen-regular-webfont.svg#oxygenregular') format('svg');
    font-weight: normal;
    font-style: normal;
}

It works fine on IE and Firefix. But there is an issue: on IE the fonts are rendered correctly only when I navigate the page using inner web page links. If I hit Refresh or Back button, the fonts are replaced by default font (Times New Roman).

Currently the website is using HTTPS but the same problem was observed when using HTTP.

When I navigate using inner website links, in the Network tab of IE Developer tools (Shift - F12), I see the following:

/Content/oxygen-regular-webfont.eot?    GET 200 application/vnd.ms-fontobject

When I use Refresh/Back buttons, there are two more entries for the other fonts as well:

/Content/oxygen-regular-webfont.woff    GET 200 application/x-font-woff
/Content/oxygen-regular-webfont.ttf GET 200 application/octet-stream

CSS file itself is being loaded in a following way:

/Content/site.css   GET 200 text/css

I tried to remove both woff and ttf so I had the following:

@font-face {
    font-family: 'oxygenregular';
    src: url('oxygen-regular-webfont.eot');
    src: url('oxygen-regular-webfont.eot?#iefix') format('embedded-opentype');
    font-weight: normal;
    font-style: normal;
}

But still IE behaves the same way (except it does not download woff and ttf any more): displays incorrect fallback fonts when navigating through Back/Refresh.

How do I make IE to load correct fonts on Refresh/Back actions?

Answer 1

I found a solution but I cannot see the reason why it works (well, only one reason - it's IE :D).

What I did was to put the same site on Apache and test again. On Apache the fonts worked fine even when using Refresh button. Then in the network inspector I saw that Apache is returning 304 instead of 200 for the eot file and it hit me - so it's caching issue. I went to my ASP.NET app and sure enough - for security reasons (and also to avoid caching AJAX requests) someone had disabled every caching you could imagine:

        // prevent caching for security reasons
        HttpContext.Current.Response.Cache.SetAllowResponseInBrowserHistory(false);
        HttpContext.Current.Response.Cache.SetExpires(DateTime.UtcNow.AddDays(-1));
        HttpContext.Current.Response.Cache.SetValidUntilExpires(false);
        HttpContext.Current.Response.Cache.SetRevalidation(HttpCacheRevalidation.AllCaches);
        HttpContext.Current.Response.Cache.SetNoServerCaching();

        // do not use any of the following two - they break CSS fonts on IE
        HttpContext.Current.Response.Cache.SetCacheability(HttpCacheability.NoCache);
        HttpContext.Current.Response.Cache.SetNoStore();

As soon as I commented out the last two lines of code, suddenly fonts started to work without problems on IE. So I guess the answer is: IE cannot load the font if it is not cached. I have no idea why the problem happens only when refreshing/navigating back, though.

Edit - Alternative solution

Instead of commenting those last two lines

    // do not use any of the following two - they break CSS fonts on IE
    HttpContext.Current.Response.Cache.SetCacheability(HttpCacheability.NoCache);
    HttpContext.Current.Response.Cache.SetNoStore();

Change the SetAllowResponseInBrowserHistory to true instead:

HttpContext.Current.Response.Cache.SetAllowResponseInBrowserHistory(true);

This should still allow no-cache with the exception of back and forward navigation as I understand it. MSDN - SetAllowResponseInBrowserHistory Method