Why is the author page in WordPress throwing a 404 error?

Question

WordPress

The author's page /blog/author/admin gives a 404 error.

What I tried to do:

1) Disabled all plugins - did not help.
2) Changed nicename several times - didn't help.
3) I put several different themes, including the default one - it did not help.
4) After each manipulation, I re-saved the "Permalinks" - it did not help.

Where could be the problem?

Answer 1

Redirects failed or RewriteEngine failed. Show the contents of .htaccess (if apache).