503 server error when I update once specific page

@catfishtpa Temporarily disabling the Yoast SEO plugin won’t cause you to lose any of the data you created with the plugin.

Can you please confirm you are using the most recent version of Yoast SEO, version 15.5? You can learn more about updating here: https://yoast.com/help/how-can-i-update-my-free-plugin/

Also, can you confirm you are using WordPress 5.6? You can check by clicking on the W in the top left and selecting About. If you need to update, please check with your host provider. Please know that if you are using an older version of WordPress Core you may experience unexpected behavior with Yoast. This guide explains more: https://yoast.com/why-we-dont-support-old-wordpress-versions/

If you update to the most current version of WordPress and Yoast SEO, does this resolve the issue?

If after ensuring that both WordPress, Yoast SEO, and your other plugins and themes are up to date the issue is still occurring, we’d next recommend performing a conflicting check to see whether another plugin or theme is interfering with the Yoast SEO Plugin. This will help us narrow down the exact cause and determine what the next steps are while saving you time.

The fastest way to do this is to?deactivate all non-Yoast plugins and switch to a standard theme?like?Twenty Nineteen.?Test this on your development or staging site, if you have one. If not, we recommend using the?Health Check & Troubleshooting?plugin. This plugin allows you to run a conflict check?without affecting normal visitors to your site.

If you’re unfamiliar with checking for conflicts, we’d like to point you to a step-by-step guide that will walk you through the process:?How to check for plugin conflicts.

All plugins are updated, and I am using WP 6.6.
Deactivated Yoast and Yoast multilingual, still same error.
I am in contact with WPML, waiting for news from them about deactivationg WPML without data loss, the I will try to deactivate that plugin.
If that has no effect I will try the full troubleshoot mode with the plugin you recommended.

@catfishtpa If the error is still occurring without Yoast and Yoast Multilingual activated, it’s unlikely that Yoast SEO is causing the 503 error. Regardless, the plugin we recommend should still help with diagnosing which is responsible.