Author Archives: ericlaw

Script-Generated Download Files

As we finish up the next release of Windows 10, my team is hard at work triaging incoming bugs. Here’s a pattern that has come up a few times this month: Bug: I click download in Edge Legacy: …but I end up on an error page: Womp womp. If you watch the network traffic, you’llContinue reading “Script-Generated Download Files”

CORS and Vary

Yesterday, I started looking a site compatibility bug where a page’s layout is intermittently busted. Popping open the F12 Tools on the failing page, we see that a stylesheet is getting blocked because it lacks a CORS Access-Control-Allow-Origin response header: We see that the client demands the header because the LINK element that references itContinue reading “CORS and Vary”

Be skeptical of client-reported MIME Content-Types

Over the 14 years that I’ve been working on browsers and the web platform, I’ve seen a lot of bugs where the client’s configuration causes a problem with a website. By default, Windows maintains File Extension to Content Type and Content Type to File Extension mappings mappings in the registry. You can find the former mappings inContinue reading “Be skeptical of client-reported MIME Content-Types”

Edge EV UI Requires SmartScreen

A user recently noticed that when loading Paypal.com in Microsoft Edge, the UI shown was the default HTTPS UI (a gray lock): Instead of the fancier “green” UI shown for servers that present Extended Validation (EV) certificates: The user observed this on some Windows 10 machines but not others. The variable that differed between those machines wasContinue reading “Edge EV UI Requires SmartScreen”