WordPress: wp-json REST API 403

If you see this error:

Failed to load resource: the server responded with a status of 403 ()
/wp-json/wp/v2/users/?who=authors&per_page=100&_locale=user:1 
Failed to load resource: the server responded with a status of 403 ()
/wp-json/wp/v2/taxonomies/category?context=edit&_locale=user:1
Failed to load resource: the server responded with a status of 403 ()
post_tag:1
Failed to load resource: the server responded with a status of 403 ()
/wp-json/wp/v2/categories?per_page=100&orderby=name&order=asc&_fields=id%2Cname%2Cparent&_locale=user:1

https://victorwyee.com/wp-json/wp/v2/taxonomies/post_tag?context=edit&_locale=user 403
https://victorwyee.com/wp-json/wp/v2/users/me?_locale=user
https://victorwyee.com/wp-json/wp/v2/taxonomies/category?context=edit&_locale=user

the first solution you should try is to log out and log back in. Or use a different browser, preferably in incognito mode. I’ve been bitten twice by this error — which shows up even when I’m logged in — and in both times, it was an outdated cookie or nonce token being sent against the WordPress API.