Why can't it find an existing file (404 error)?

Question

Nginx

Firebug gives the following:,
but when you go through it, "Open in a new tab" the file opens successfully.
What could be the problem?
The server issues the code for this file, but it exists. Help me please.
Result from mainspy.ru/answer_servera :

Answer 1

There were problems in nginx. Reconfigured - everything worked.

Answer 2

See server logs