What does it mean?
This error occurs when you're using a field somewhere that no longer exists. The field is still used in the categories, rules, finalize or build step of an export (Feed, Marketplace or AdWords), but Channable can no longer find it in your import. You probably renamed the field in the import mapping or you have replaced your original feed with another import feed that doesn't contain this field.
The situation you will find will probably look similar to this:
How can I fix it?
There are a few options here, it depends a bit on why the field is no longer in the import field.
1. You renamed the field in the import
If you know you renamed this field in the import mapping, you could just click the red colored field in the categories, rules, finalize or build step and select the new name for the field you changed. You could also go to your import mapping and change the name of the field back to its original name.
2. The field got removed from the import
In some cases you might have accidentally removed the field from your import mapping. This can only happen when the missing field was a field that you've added as a new field, in addition to the fields that we're already in your import feed. A new field is all the way at the bottom of your import mapping and looks like the field in the red square below:
If you've accidentally removed the new field from your import mapping, you can simply add the new field again (see "Add new field" section in this support article).
3. Your whole import feed got replaced by another import feed
In this cases you will probably see a lot of different fields missing in the rules, finalize or build from your exporter. In this case it will probably take a bit more effort to fix the missing fields issues, because the import feed contains completely different fields now.
In this case it's best to take your time to look at which fields the new import feed contains. It's best to walk through all steps of your exports completely and to re-do the setup of your exports. This way you can make sure that your rules are doing what you want them to do again and that your exports contain the correct product information from your import feed.