It looks like that field must be of type "number" and be limited to one value like you see in the image above. The "number of values" fieldset should be on the content type's manage fields page, e.g. "admin/structure/types/manage/<content-type>/fields/<field-of-type-mailchimp-subscription>".
I would check the manage field page to make sure it is set to one for the number of values allowed.
I don't know if this will be considered spam, but here is a link to a website (in Bulgarian only) with Ubercart and Backdrop that I have been developing and maintaining for several years....
Posted13 hours 21 min ago by Antony Milenkov (amilenkov) on:
I have worked years ago with both Drupal Ubercart and Drupal Commerce. I think Drupal created Commerce as an alternative to Ubercart with a motive to commercialize its own e-commerce module as...
Posted13 hours 59 min ago by Antony Milenkov (amilenkov) on:
Its not like 10 years ago, content is content, store is store, content + commerce is in most of the website today. backdrop is not in the position to fight with wp and drupal, but if backdrop...
Facebook permissions are a separate issue. But certainly no module can bypass them. It may be worth reconsidering how to separate the private and public sides of the process, it's up to you to...
All that remains is to find volunteers who will do this.
In fact, now is the time for marketplaces; in other cases, for quick integration with various systems, it is easier to use...
Comments
The specific error you are seeing comes from https://github.com/backdrop-contrib/mailchimp/blob/1b970f66c112e88d2ccfe....
It looks like that field must be of type "number" and be limited to one value like you see in the image above. The "number of values" fieldset should be on the content type's manage fields page, e.g. "admin/structure/types/manage/<content-type>/fields/<field-of-type-mailchimp-subscription>".
I would check the manage field page to make sure it is set to one for the number of values allowed.