1. New profile, start firefox 2. Load www.wbeta.com 3. Click on a link on the left hand side, under 'XML News Aggrigator' 4. Exception is repeatedly thrown in a dialog: [Exception... "Component returned failure code: 0x804b000f [nsIXMLHttpRequest.setRequestHeader]" nsresult: "0x804b000f (<unknown>)" location: "JS frame :: http://www.wbeta.com/index.js :: sendReq :: line 232" data: no] No exception thrown: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.9a1) Gecko/20060504 Minefield/3.0a1 ID:2006050405 [cairo] Exceptions thrown: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.9a1) Gecko/20060505 Minefield/3.0a1 ID:2006050511 [cairo] http://bonsai.mozilla.org/cvsquery.cgi?treeid=default&module=PhoenixTinderbox&branch=HEAD&branchtype=match&dir=&file=&filetype=match&who=&whotype=match&sortby=Date&hours=2&date=explicit&mindate=2006-05-04+04&maxdate=2006-05-05+12&cvsroot=%2Fcvsroot Trunk builds after 2006-05-10 crash @ nsXMLHttpRequest::StreamReaderFunc with the same reproduction steps. See bug 361773.

I guess before the patch for bug 198595 the event argument wasn't passed on to the function, but after the patch for bug 198595 , it does. On http://www.wbeta.com, it causes the xmlhttrequest to fire again, which sets req.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded; charset=UTF-8'); again on an existing xmlhttprequest object, which throws the exception.

So this seems like a tech evangelism issue to me.

I came to the same conclusion in bug 361773 comment 13 (I also think it's Evangelism). The designer of this site were just unlucky to depend on a Firefox bug that got fixed.

Yeah, I'd say evang. The plan for the W3C XMLHttpRequest spec is to eventually require an event arg here, as I understand.

I just sent a mail to wbetamaster@msn.com regarding this.

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