Unable to set 'country of manufacture' attribute to be comparable on frontend

[tsmith1985]

Unable to set 'country of manufacture' attribute to be comparable on frontend.

Preconditions

• Magento CE v2.1.5
• PHP v7.0.14
• MySQL v14.14 Distrib 5.7.16, for osx 10.12

Steps to reproduce

1. Log into Admin
2. Navigate to Stores > Attributes > Product
3. Click on country_of_manufacture.
4. Navigate to Storefront Properties.
5. Set Comparable on Storefront to Yes.
6. Open browser dev tools to view errors console.
7. Click Save Attribute.

Expected result

1. Attribute is saved.

Actual result

1. Attribute fails to save and error message is returned from server.

[martinhetschel]

Same problem, but 503 error

[veloraven]

I'm closing this issue as duplicate of #9153.
We already have internal ticket MAGETWO-6971