My First Law of Browser Quirks was introduced a while ago : If there’s a way for a site to take dependency on a browser quirk, and break if that quirk is removed, it will happen . The Second Law of Browser Quirks is: If there’s a way for a site to combine a set of browser quirks to yield...

Inside Internet Explorer’s Tools > Internet Options > Advanced dialog, there’s an option named Enable Integrated Windows Authentication : This preference is stored using a REG_DWORD named EnableNegotiate inside HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings...

I continue to be amazed at how often site-compatibility issues turn out to have a root cause related to User-Agent sniffing. For instance, earlier this year, someone wrote into the comments section on one of my posts noting that the HTML5 canvas art site WeaveSilk.com wasn’t working in IE9....

As announced over on the IEBlog , the first update for IE9 is now available. When this update is installed, the IE Help > About screen will indicate that the IE version is 9.0.1. Please note that this is a display only change and it is not reflected in the User-Agent String, Conditional...

In Internet Explorer, if you press F1 or use the Help menu, the Windows Help and Support screen will show. However, you may find that you always see a Topic not found error message. The reason is that Internet Explorer 9’s help files are available only online. To see the help content...

An amusing April Fool’s satire I ran across yesterday reminded me of a Connect bug that was reported back in the IE9 Beta. The HTML <video> control’s default context menu includes a “Save Video As…” menu option that allows saving the video to disk: The...

Recently, a user sent in the following screenshot of a security warning they encountered when attempting to download the Microsoft Zune software: Obviously, we immediately attempted to reproduce the reported problem, and we found we were unable to do so – the program was recognized as legitimate...

I recently encountered a blog that isn’t looking right in IE9: The site renders just fine in other browsers, and when the page is put into Compatibility View by ticking the icon in the address bar: What’s going on here? It’s clear that a stylesheet isn’t...

As we explore network performance on the “real-world web”, one bad pattern in particular keeps recurring, and it’s not something that our many IE9 Networking Performance Improvements alone will resolve. The bad pattern is the use of Connection: close semantics for HTTPS connections...

Back in the summer of 2009, I blogged about Windows 7’s new support for TLS 1.1 and TLS 1.2 . These new protocols are disabled by default, but can be enabled using Group Policy or the Advanced Tab of the Internet Control Panel: Some adventurous Internet Explorer users have found that...

A few weeks ago , I discussed one compatibility issue we’d found when running a new HTML5 game . The game’s developers quickly fixed their site to return a proper character set declaration and we were able to get the game running in IE9. However, after playing the game for about 5 seconds...

Note: I mentioned this problem before ( Troubleshooting Login Cookies #3 ) but it was buried in a long post and this is an issue that lots of folks inside Microsoft hit, so I’m pulling it out into its own post. The Problem From time to time, various users have complained to the IE team that...

The WinINET API allows the caller to specify the accepted MIME types for a given HTTP request by passing a null-terminated array of null-terminated strings using the lplpszAcceptTypes parameter. When calling the HttpOpenRequest API, applications must take care to either pass NULL, or a pointer to a properly...

I recently heard from some users who are seeing lower-than-expected scores on the Speed Reading and FishIE Tank benchmarks. I went to check these tests myself and found that my laptop’s score was low. In fact, it was much lower than I’d seen last year. What happened? First, a bit of background...

Technical Evangelist Giorgio Sardo just published a great post about HTML5 Canvas, responding to some concerns about bugs in the IE9 Beta. The post also takes a quick look at cross-browser interop for the Canvas object. It’s definitely worth the read: http://blogs.msdn.com/b/giorgio/archive...

Several months ago, I blogged about IE’s support for International Filenames on Downloads . Today’s post is a bit simpler and describes two cases when IE may rename downloaded files. Filename Extension and QueryString Parameters If a file download HTTP response does not contain a Content...

From time-to-time, web developers contact the IE team reporting that they’ve encountered a problem whereby Internet Explorer submits a POST but fails to transmit the content body. This bodyless POST indicates via the Content-Length header that the POST is zero-bytes long, regardless of how much...

Update: This regression, introduced in IE9 Beta, was fixed in IE9 RC. We recently had a report over on the IEBlog that SOCKS proxies are not supported by IE9 Beta. That observation is correct, and a regression from prior versions of Internet Explorer; IE9 Beta simply ignores the SOCKS proxy if one...

One of the commonly reported bugs on Connect is that Google Image Search shows grey boxes for some of the images in IE9 Beta. I had a quick look at the site this afternoon, and I can easily reproduce the problem , as you can see in the screenshot below. Now, I tend to debug things first from...

While many web developers find subtle browser behaviors baffling, often browser developers are bewildered by web content. Yesterday, we ran into an interesting site compatibility problem that occurs in the latest internal version of IE9. The site in question is a popular site which uses a Flash applet...

All joking aside, last fall, I wrote about the variety of reasons why Internet Explorer might not offer to remember your password on a web form. As I mentioned then, you will not be re-prompted to save your password if you’ve previously declined to store the password for this username on this page by...

A Windows 7 user of Fiddler encountered an interesting error this morning, and it reminded me of an interesting HTTPS compatibility problem we found in the Windows Vista timeframe. The user is trying to visit https://www.atsenergo.ru with Fiddler running in HTTPS-decryption mode. Fiddler uses the...

Many years ago, Microsoft developed an implementation of a Java Virtual Machine to run Java content. Internet Explorer 5 included code that would download and install the JVM (if needed) when a user encountered Java content on the web. After some time, support was discontinued for the Microsoft JVM,...

Over the last few weeks, I’ve been exchanging mail with a webmaster (Vladimir) in Russia who reported that his customers were having problems using IE8 on Windows 7 to log into his website. His site uses HTTP Basic Authentication, so users are prompted to enter their credentials using the following dialog...

Internet Explorer 8 removed support for one of my favorite browser features: Inline AutoComplete (IAC) for the address bar. This feature was off-by-default, but for almost a decade the first thing I did when setting up a new computer was enable IAC using the checkbox Tools > Internet Options >...