Explanation of error code APNX-1-4205-003

I got the same error when I updated my List View. It was because I didn't surround the Facet label and Option label values with double quotes.

It wasn't easy to find the problem because I was used to the behavior on Forms, where if there is an expression editor option you can still enter text directly (for example on the Form Title).

The error message could be more informative, however. It was finally this page that explained the issue:
forum.appian.com/.../Record_Design

...where it says:
Initial Option Label: Expression that defines the name of the first facet option displayed to end users. For example, "North America" displays as North America.

I got the same error when I updated my List View. It was because I didn't surround the Facet label and Option label values with double quotes.

It wasn't easy to find the problem because I was used to the behavior on Forms, where if there is an expression editor option you can still enter text directly (for example on the Form Title).

The error message could be more informative, however. It was finally this page that explained the issue:
forum.appian.com/.../Record_Design

...where it says:
Initial Option Label: Expression that defines the name of the first facet option displayed to end users. For example, "North America" displays as North America.