What triggers this issue?
This issue reports pages with at least one URL in hreflang annotations returning HTTP status code different from 200 (OK).
Why is it important?
If your website serves different content based on a user's language or region, you should use hreflang annotations to help search engines, such as Google, to point users to the most appropriate version of your page, depending on users' language and region.
If hreflang URL does not point to a valid live page, hreflang annotations may be ignored or not interpreted correctly. Consequently, search engines may "overlook" alternate versions of your page and will not be able to point users to the most appropriate version of your page by language or region.
How to fix it?
Check the "Hreflang links" column for the pages listed in this report. There you should look for the URLs that do not return the 200 (OK) HTTP status code (e.g. 301, 404, etc.)
For 3xx (Redirection) status codes
Replace the hreflnag URL with the direct link to the destination page to avoid the unnecessary redirection.
For 4xx (Client Error) status codes
The most common 4xx errors are 404 (Not Found) and 410 (Gone). Links to moved or deleted pages on your website usually cause these errors. Also, there may be a typo in the hreflang URL.
You can either restore the moved or deleted page at its old URL or remove that URL from hreflang annotations if you don't have a replacement for it. If you do, place it instead of the 4xx URL in hreflang annotations.
You should note that each language page should specify all the different language versions, including itself. In other words, each page version must have the exact same list of hreflang links. So you should make sure that you edit the hreflang annotations on all pages in the group.
429 (Too Many Requests) HTTP response codes on hreflang URLs can be caused by the high crawling speed set in your project settings. Reduce the speed in the crawl settings and run a project re-crawl.
For 5xx (Server Error) status codes
5xx response codes indicate an issue with the web server. You might need to address your developer or hosting provider to find the cause. Your server may be misconfigured, overloaded, or generally slow.
You can learn more about 5xx errors in Site Audit here:
What does ‘5XX page’ error mean in Site Audit?