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This page contains some of the interesting IE bugs I've come across in working with the community.  These issues are known to the IE team, and may be addressed in future releases.  Some of these issues are extraordinarily obscure or minor, and only of academic interest.

Bug count: 13.  Last update 5/24/2012.

An issue list for IE8 can be found here.

Another bug list for IE7 can be found here.  I have no relationship with that site and cannot vouch for anything you find there.

End-User Bugs

IE0008: Wrong folder when opening a FTP site inside IE

IE7 no longer opens FTP folders in Folder View by default; it instead shows a HTML directory listing.  This change exposes an existing limitation in WinINET's FTP code.  Specifically, WinINET will erroneously CWD / after logging in, and that will take the directory context out of the "user directory" if the server had specified one.

Web Developer bugs

IE0001: XMLHTTPRequest overly-aggressive caching

Internet Explorer's XMLHTTPRequest object may cache and reuse the response to a GET request if the server does not send any headers prohibiting caching.  Workarounds: Either use the POST method, a random query string, or (best) configure the server to send proper cache directives.  Note: Using a non-random query string alone is not enough to prevent caching.

While RFC2616 has always indicated that servers SHOULD be explicit about expiration times, the HTTPBIS draft appears to be dropping the requirement that URLs with query strings are not generally cacheable.

IE0003: Slow scrolling with CSS background of Transparent PNG

Users may experience poor performance in IE7 when scrolling pages that have large regions with a transparent PNG background, where the PNG used is very small (e.g. 1px by 1px). 

You can work around this performance problem by using a larger (wider/taller) transparent PNG file.  

IE0004: Slow scrolling with use of CSS :hover rules

Users may experience poor performance in IE7 when scrolling pages that contain large numbers of elements with :hover rules.

IE0005: By-design.  Setting cookies fails when the hostname of the server contains an underscore.

This happens because the machine name contains an underscore, technically prohibited by DNS rules (LetterDigitsHyphen) and hence blocked. This issue is mostly relevant for Intranet sites; most DNS systems will prohibit use of underscores in hostnames due to the LDH rule.  See for more info.

IE0006: By-design.  Setting more than 20 50 cookies per host results in the oldest cookie being lost.

In August 2007, the IE team increased the cookies per domain limit from 20 to 50.  For more information on this change, and on IE cookie handling in general, check out the IEBlog announcement.

WinINET meets the minimum cookie recommendations in the standards.  See for the size and count limits for cookies in IE.

IE0007: "Operation Aborted" error message when a page finishes loading

This happens because you have some script inside a child container element trying to modify a container element in its parent chain.  See for more info.  This issue was partially resolved for IE8; see

IE0009: Incorrect Mixed Content warning on pages that use the Javascript Protocol

Expect: No mixed content dialog.
Actual: Mixed content dialog.
Analysis: IE does not consider the Javascript URI protocol secure for the purposes of HTTPS.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "">
<html xmlns="">
<!-- Why you would want to do this, I have no idea. -->
<script defer="true" src="javascript:void(0);"></script>
This page does not do any unsecure downloads and should be considered secure.

Note: IE5/6 additionally encounters the Mixed Content warning when the URI about:blank is used. That additional limitation was resolved in IE7 Beta 3.

IE0010: VML cannot be used on Strict mode pages

When an HTML page uses the !DOCTYPE element in Windows Internet Explorer 7 or in Microsoft Internet Explorer 6, a Vector Markup Language (VML) element is not displayed in strict mode. Workaround available, see:

IE0012: IE Travellog broken when navigating back/away from a page with a large POST form

If there is a form input field with a value longer than 523,659 characters, when you navigate away from the page, IE may clear the current session's travellog (similar to history), disabling the back and forward buttons.

Repros in IE6 & IE7.

IE0013: IE XMLHTTP implementation turns 204 response code into bogus 1223 status code

Described here, the XMLHTTPRequest object in IE will return a status code of 1223 and drop all response headers if the server returns a HTTP/204 No Content response. 

This is caused by an internal design artifact of URLMon (binding returns Operation Aborted (1223) if the server returns no content in response to a request).

Repros in IE9 and earlier. Update: Fixed in IE10.

Workaround: Treat "1223" as equivalent to a 204.  Note: HTTP headers remain unavailable in this case.

Application/Server Developer bugs

IE0002: Fragment lost when FILE URL passed on command line

Internet Explorer 7 no longer successfully tracks the fragment when IE is started with a URL on the command line.  For instance, iexplore.exe file://C:/somepage.htm#fragment is started from the command line, IE navigates to somepage, but not to the bookmark in the page named fragment.

IE0011: Internet Explorer may send a CRLF after a HTTP/1.1 POST body, without accounting for it in Content-Length

Internet Explorer may send 2 extra bytes trailing a post body if the server is believed (often incorrectly) to potentially be a HTTP/1.0 server.

This issue is mentioned here:

This issue was fixed in Internet Explorer 8.