Why when entering the admin panel: 503 Error Page not found (Modx Revo)?

Question

MODX

Hello!
The essence of the problem:
When I click on the link: http://my-site/manager , I get to a page with an error:
503 Error
Page not found
The page you requested was not found
And the whole frontend works.
The problem started after I clicked "end all sessions" in the admin panel.
For when I was in the admin panel, the manager could no longer enter the admin panel, he received a 503rd error.
Here is the error log:

[2015-09-16 11:31:40] (ERROR @ /index.php) array (
  0 => 25,
  1 => 26,
  2 => 27,
  3 => 28,
)

Question:
How to solve the problem?
PS. Logged in via ftp, cleared core/cash - didn't help.

Answer 1

Thank you for your attention. Problem solved. The reason was in one of the plugins.

Answer 2

I'm sorry, is the link correct?