My first Win8 + IE10 App Compat Issue

So I’ve been loving the full screen, fast, add-on free, HTML5 IE10 in Windows 8. But unfortunately attempting to logon to internet banking wasn’t working.

Front page of http://www.netbank.com.au OK…

image

Then Boom! Total failure

image

Now of course this could be caused by bad internet connection or the target website was down. But I tested on IE9 in a VM on the same machine, using same network, and no problem. Logon great. I tested on two different Windows 8 machines just to make sure it wasn’t just my machine, both failed to logon.

Now the full screen IE10 “metro” version of IE runs with no add-ins, so thought it wise to test in full browser mode so see if things faired any better. I did this by clicking “page” icon and Use Desktop View

image

This didn’t offer any more success. However it did give me access to the wonderful developer toolbar, enabled via F12 key press.

Before each test I have a habit of using the “delete cache” button to ensure no interference from cached data.

image

I then started Network capture. You can do this by pressing F5 when developer toolbar has focus, or hit Network tab then Start Capturing

Often if a webpage is not working you will see the broken page “Compatibility View” icon in the address bar.

image

However this icon was not available for this page. We can see why from the network capture. Looking at detailed view we see X-UA-Compatible set to IE=EmulateIE7 which tells IE to use compatibility view automatically. However if you look up the top of developer bar you will see two important things

  • Browser Mode: IE10
  • Document Mode: IE7 standards

image

The developer toolbar can let us change the browser or document mode for testing. So I set the document mode to IE9 and also did a network capture. This time the site worked! During the network capture I noticed something strange…

In Browser Mode: IE10 (Broken)

image

In Browser Mode: IE9 (Working)

image

OK so there is a 0.35 KB difference between the two. Interesting. Doing this multiple times found in the same browser mode there was always a difference but only 1-4 bytes difference, not this much bigger difference. So if the server is giving us different responses what could cause it? Typically this is a result of different Request Headers. Looking at the detailed view of network capture we can see the differences

In Browser Mode: IE9 (Working)

image

In Browser Mode: IE10 (Broken)

image

We can see even though IE7 standards mode is used, the User-Agent string still shows the current browser version.

But to be sure this was a cause I got the response body of the good and bad pages and WinDiff’ed them. The bad one had a different action on post…The bad one is in yellow.

image

This matched up to the network monitor…the good logon…

image

The bad logon…

image

To fully completely test this was the pure cause I had to use Fiddler. (http://www.fiddler2.com) Fiddler has a great feature which allows us to drag captured web requests and replay them. You can then edit fields and change as necessary.

So I sent two requests with Fiddler

Test #1

image

Test #2

image

And the results confirmed what I had found…Just by changing the versions of MSIE two different page results.

image

And yes…the 2nd bad one had the non-existent URL in the post action.

So this time can’t blame IE! The server is giving us wrong page. Have to let the webmaster know.

But I expect this will become a common problem…As we saw in Windows XP with dodgy developers/packagers testing for OS version like

If (MajorVersion >= 5 && MinorVersion >=1) then Install

I expect we will see more issues related to the IE version changing from one digit “9” to two digits “10” as some interesting version check logic breaks down…especially if version number comparison is done as a “string” not a  “number” …

About chentiangemalc

specializes in end-user computing technologies. disclaimer 1) use at your own risk. test any solution in your environment. if you do not understand the impact/consequences of what you're doing please stop, and ask advice from somebody who does. 2) views are my own at the time of posting and do not necessarily represent my current view or the view of my employer and family members/relatives. 3) over the years Microsoft/Citrix/VMWare have given me a few free shirts, pens, paper notebooks/etc. despite these gifts i will try to remain unbiased.
This entry was posted in Internet Explorer, Windows 8 and tagged . Bookmark the permalink.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s