Microsoft is set to release Windows 10 pretty soon and with it comes a new way to set the default browser for your system.

Previous versions of Windows had an API that allowed applications to set themselves as the default application. This worked well and allowed web browsers like Firefox and Chrome to have a single click within their interface to set themselves as the default browser. No extra work was needed by the user after clicking the button within the respective app.

Starting in Windows 10, references to this API now generate the following error dialog on the machine:

Obviously, this message isn’t that helpful. First, users who click on a button to “Make Firefox my Default Browser” now get a dialog telling them what to do instead of doing it for them. Secondly, the message is given in a prompt that blocks interaction with the rest of the computer until the OK button is clicked. Combining this second issue with the lengthy list of steps that the dialog provides makes the situation even worse, as the user will have to memorize this 3-step process before clicking OK.

This experience isn’t something that we want to ship to Firefox users. When I first saw this experience, I sent an email to some people working on Chrome to ask them what their plans were to solve this. They said that they had looked in to this and decided they would instead just open the Settings app to the Default Applications view.

I brought this approach back to some of my coworkers and we decided we would match the behavior that Chrome was using. After all, it didn’t seem like a better solution existed and we certainly didn’t want our users to be seeing the ugly dialog described above.

After I landed the changes in Firefox to open the Settings app, Masayuki Nakano provided an alternative implementation that would open a friendlier looking dialog to set the default application.

This dialog looks a lot better, but it only sets the choice as the default browser if the small “Always use this app” checkbox at the bottom is checked before the OK button is clicked.

Once we had two implementations, we ran an A/B test of them for a week with our Nightly audience.

Key Count Percentage set as Default Alternative Approach/OpenAs (users who did not set the browser as default) 2.35k 53% Alternative Approach/OpenAs (users who did set the browser as default) 2.65k Settings (users who did not set the browser as default) 2.76k 50% Settings (users who did set the browser as default) 2.86k

The table above shows the data that was collected through the A/B test from June 22 to June 29 with Firefox Nightly 41. This data showed that 53% of alternative-approach users set Firefox as default, whereas 50% of the Settings-app users set Firefox as default.

With only a week of data, we didn’t see a statistical difference between the two approaches and decided we would stick with the Settings app due to it’s wider adoption. We also had issues with the OpenAs approach where we weren’t able to register all protocols and file extensions.

Next Steps

The default browser situation on Windows 10 is pretty bad. There is more work that we can and should do in the Windows 10 upgrade experience to retain users (the default upgrade changes the default browser to Edge).

We also would like to improve our telemetry tracking of the default browser dialog. Ideally we could use some accessibility or automation APIs to scroll into view the Default Browser option within the settings app (it’s scrolled out of view when it is first opened).