seo – Hreflang reciprocal missing (no return tag). Some pages do not include hreflang links to all other pages in the group

There is an error while testing my site on https://ahrefs.com/:

Reciprocal Hreflang missing (no return tag)

It suggests:

Why and how to fix

Details of the problem

There are missing confirmation (return) links for pages declared in hreflang annotations.

If page A refers to page B in hreflang annotations, page B must be linked to page A in return.

See Google's guidelines on the implementation of "hreflang" here.

How to repair

To avoid this problem, make sure that all page versions translated or intended for users in a given region have the same set of hreflang annotations.

I tried to solve this problem, but I could not succeed.

Another site (https://hreflang.org/missing-return-tags-error-for-hreflang/) suggests:

  • All pages use the same set of tags for Hreflang. This is the easiest way to remember how to implement your tags.
  • Each page refers to itself. that is, page A will include a link to itself in one of the Hreflang tags. It does not just create a link to pages B and C.
  • Pages B and C should also include Hreflang tags (exactly the same)

Google Webmaster Tools will report this error, but it is too late to detect errors. Ideally, you want to look for Hreflang errors on your site before Google's robot.

If Google reports these errors, it is likely that one or more of the following problems have occurred:

  • Page A is the main page. It is linked only to its alternative versions (pages B and C), but not to itself.
  • Pages B and C do not include any Hreflang tags.
  • Pages B and C do not include the same set of Hreflang tags. They omit one or more links.

"If Google reports these errors, it may be that one or more of the following events have occurred:"

This problem is terrible. How can I solve this problem?