Why does Yandex give a 401 error?

Question

MODX

There is a fully working site. All pages are working.
When you try to add a link to direct, some pages of the site give an error 401 Unauthorized
At the same time, everything opens and works
The site is on mods
What could be the matter?

Answer 1

Better put the tag not only Yandex but also modx.
Start by looking at the logs on the site - how does a Yandex visit look like for you there.