At CMS Hub launch we announced themes. We are rolling out validation for the theme fields.json to help theme developers. Errors in the file will be publish blocking, preventing you from adding invalid code that won't work. This is rolling out in two phases to give developers of existing themes the ability to fix any issues before the errors will show in the Design Manager.

What's happening?

To make developing themes easier, we are rolling out validation errors for the fields.json file. Pages created with themes that have errors will not be impacted. Errors will display on the theme fields.json file itself and will prevent publishing of this file until the errors are resolved.

New themes created after July 27

New themes will have validation enabled right away, helping you to put out a quality working theme right away. Your code will have to be valid before publishing is allowed. This prevents you from writing code that is invalid, and would result in an unexpected result.

Existing themes will get validation August 17th

For existing themes, we wanted to give developers a heads up before we started displaying the errors. You work hard on your themes and we want to help you look good. To prevent alarm from customers who might open the file and see errors, existing themes will not get validation until August 17th.

During this time we encourage you to test your theme fields.json against a temporary validation API we've created for this. This allows you to see the errors before they are revealed in a way customers can see them. Use that to correct your fields.json as necessary, to have confidence that errors will not display when we enable validation for existing themes.

UPDATE: The temporary API has been taken down because validation is now live for all themes in the Design Manager and local development tools.

Once validation starts for existing themes the design manager will display the errors in context. The CMS CLI will also start returning the errors on upload. Publishing will be prevented until the issues are resolved.

When is it happening?

New themes created after July 27th will have validation enabled. Existing themes created before that date will not get validation right away. Validation for existing themes will start on August 17th.

Join the discussion in the developer forums if you have comments or questions.