Eslint doesn't work on emacs complaining about "Checker definition probably erroneous"

Question

I am trying to configure eslint on emacs by writing this in .emacs:

(setq flycheck-disabled-checkers '(javascript-jshint)) (setq flycheck-checkers '(javascript-eslint)) (add-hook 'js-mode-hook (lambda () (flycheck-mode t) (tern-mode t) )) 

What I get when trying to open js files is this error message:

Just an updated version of eslint to the latest version (1.3.1) and emacs to the latest version (24.5). Hope this helps.

This is not true.

(I have many old packages in the ~/.emacs.d/elpa that have remained since installing them in the previous version of emacs (24.3). But I don’t think it causes any problems).

Could you suggest how to solve this problem with eslint?