Affected versions

• Latest Nightly 81.0a1
• Firefox Beta 80.0b3

Unaffected versions

• Firefox 79.0 RC

Affected platforms

• Windows 10 64bit

Steps to reproduce

• Have one address saved. Have the following prefs: extensions.formautofill.available - on and extensions.formautofill.creditCards.available - true

1. Start Firefox
2. Visit https://www.bestbuy.com/
3. Add a product in Cart and go to checkout as Guest
4. Click on First Name field and select an entry.

Expected result

• Address field is filled by selecting an entry from autofill.

Actual result

• Address field is not filled when selecting an entry from autofill, even more, if clearing the other entries, autofill can't be used anymore (page refresh is required to make it work again).

Suggested Severity

• I suggest to mark this as a S2 severity since it impacts a highly used shopping website and based on the fact that the user will have to refresh the checkout page in order to make the autofill work again.

Regression range

• First bad: 2020-07-10
• Last good: 2020-07-09
• Pushlog: https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=63b8480782c85e2365d5fa9486c32b7ab223e998&tochange=2fcd5b42215a23aa79307fd2dfd944e25d7c6c5e
• Potential regressor: Bug 1604807 - Clear form dropdown menu appears right after telephone or credit number are filled

Additional notes

• Gif showing the issue is attached. Left - Good build, Right - Bad build.

Thanks for tagging me, Bogdan. This is a kind of perplexing effect from the change you point to, but I agree that it's a prime suspect. At the moment, I don't have any theories about why this is happening, so it'll require additional debugging. I'm clearing my ni? to let this go through the normal triage process.

Not cc autofill related.

Fixed by Bug 1658086

Verified - Fixed in latest Nightly 81.0a1 (build id: 20200813092915) using Windows 10, Ubuntu 18.04 and Mac OS 10.13. All the expected fields are autofilled now. Works fine after clearing the other entries as well.