Hello Phil,
Thanks for the clarification. We believe you were running the SEO data optimization analysis when that error occurred. Your server returned a 403 error when our plugin was making a request to the REST API.
The Yoast plugin uses the WordPress REST API for several features, including SEO data optimization. Therefore, the pathway wp-json/yoast/v1/indexing/prepare/ is a request that our plugin makes to the REST API for scanning posts and index them in the website database.
It looks like something on your site/server setups blocks them. Therefore, SEO data optimization cannot be performed.
Because we don’t know your server setup, we cannot determine exactly why the server returns a 403 for the REST API requests made by Yoast. Based on similar issues we receive from other users, this typically occurs due to a security or server setting.
Would you please check the ‘mod_security’ settings that prevent our plugin from accessing the REST API? If there are no ‘mod_security’ settings preventing access at the server, you may have a custom .htaccess rule or security plugin limiting access to the WordPress REST API. Please review any security restrictions and whitelist the Yoast plugin for accessing the feature. You need to whitelist all the yoast.com and my.yoast.com URLs.
If you have a Web Application Firewall (WAF), like Comodo, please verify that it is not set up to strip the parameter from the Yoast REST API requests. Some users have reported that some WAF setups are too strict to prevent Blind SQL injection attacks.