marking as untriaged and requesting dev team to check the issue.

I am seeing the same behavior on a few sites that I maintain as well. To add a bit of detail (because I see the same situation on ryanair.com as with my sites,) I noticed that it is an issue when the month is a select box and the option values are type-qualified (value="number:1" for January, e.g.)

Changing the select box to have non-dynamic options without type qualification allows autofill to work properly. 

Further, this was working for Chrome version 48.0.2564.116, and it broke with the update to 49.0.2623.110 (or one of the updates in between those two versions.)

If I find any more detail that might help the diagnosis, I will add it here.

Thanks Mark, are you using a library or framework to construct the Month/year expiration fields? Putting value="number:1" is not a standard was of doing things.

Yes, I am using AngularJS, which is what ryanair.com is using as well (based on looking at their javascript.

Incidentally, I thought that looked strange, and was curious what part of a standard that would be.

Thanks, is there a component that does credit card entry natively in AngularJS or is credit card entry party of a plugin? Sorry, I'm not familiar with it and could not find such a plugin by searching.

Oh, sorry. No, it is not part of a plugin. We are converting an object (key-value pairs of month name to number) via Angular's ng-options directive:

<select ng-model="payment.ExpMonth" ng-options="cardMonth.Value as cardMonth.Name for cardMonth in cardMonths" class="select" name="expMonth" required>
    <option value="">Month</option>
</select>

Where cardMonths is defined like so:

    $scope.cardMonths = [{
        Name: '01 (January)',
        Value: 1
    }, {
        Name: '02 (February)',
        Value: '02'
    }, {
        Name: '03 (March)',
        Value: '03'
    }, {
        Name: '04 (April)',
        Value: '04'
    }, {
        Name: '05 (May)',
        Value: '05'
    }, {
        Name: '06 (June)',
        Value: '06'
    }, {
        Name: '07 (July)',
        Value: '07'
    }, {
        Name: '08 (August)',
        Value: '08'
    }, {
        Name: '09 (September)',
        Value: '09'
    }, {
        Name: '10 (October)',
        Value: '10'
    }, {
        Name: '11 (November)',
        Value: '11'
    }, {
        Name: '12 (December)',
        Value: '12'
    }];

Thanks for taking a look at this!

Whoops. I was testing a few things while looking at this, and I botched some of it. All of the Values in cardMonths should be integers, not strings.

Thanks Mark for the details. So AngularJS will take the "Value" attribute and transform it to "number:<Value>" (e.g. "number:1")? If so, sounds like Autofill should adapt to that.

Yes, exactly. I believe it puts in the data type so it can keep two-way binding working (I'm speculating on this though.) If the value were a string, it becomes "string:<Value>".

Looks like we have seen "number:" in the wild for exp month so I'll fix that and hold out of checking for "string:"

Thanks for your help in making Autofill better!

Thank you!

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d9f8818992a4f18090aeca2cfff70dfc9504571b

commit d9f8818992a4f18090aeca2cfff70dfc9504571b
Author: mathp <mathp@chromium.org>
Date: Fri Apr 22 15:50:45 2016

Autofill: Check for common angular js prefix when filling exp month.

BUG= 602987 
TEST=AutofillFieldTest

Review URL: https://codereview.chromium.org/1905143002

Cr-Commit-Position: refs/heads/master@{#389121}

[modify] https://crrev.com/d9f8818992a4f18090aeca2cfff70dfc9504571b/components/autofill/core/browser/autofill_field.cc
[modify] https://crrev.com/d9f8818992a4f18090aeca2cfff70dfc9504571b/components/autofill/core/browser/autofill_field_unittest.cc