Preview's not working due to CORS error

[drewbaker]

When trying to use Fuxt in preview mode, it is including cookies in the request. The backend needs to be ready to accept these, otherwise a CORS error is thrown.

For example, see this error in Firefox when trying to fetch a draft page:

The problem is described here:
https://stackoverflow.com/a/69479005/503546

And the solution for WordPress WP JSON API is shown here:
https://stackoverflow.com/a/57951582/503546

[rsm0128]

@drewbaker For Gnet, I had a test on both Firefox and Chrome, but don't get the CORS error.

wp-restapi adds the headers in WP core. Here is the code block that adds the CORS header.
https://github.com/WordPress/WordPress/blob/master/wp-includes/rest-api.php#L776-L793

In my opinion, the preview returns 500 error was related with SSG configuration. It seems like preview works fine for the Gnet now. (I guess it's related with recent changes)