Company mode (Emacs plugin) back-end could not be initialized?

Every time I initiate company-mode with M-x company-mode this message shows up:

Company back-end 'company-semantic' could not be initialized
Company back开发者_StackOverflow社区-end 'company-ropemacs' could not be initialized
Company back-end 'company-pysmell' could not be initialized

The completion works but I wonder whats the meaning of that message and how to fix it.

EDIT: I moved company-semantic.el company-ropemacs.el company-pysmell.el to ~.emacs.d\plugins\company-0.4.3\unused-backends but I'm still getting that error.

Instead of changing your company-mode install directory. Just define company-backends in your .emacs file. E.g.

(setq company-backends '(company-elisp 
                         company-ropemacs
                         company-gtags
                         company-dabbrev-code
                         company-keywords
                         company-files 
                         company-dabbrev))

Excluding the backends you do not want to support from the list.

semantic, ropemacs and pysmell are all emacs extensions. Do you have them installed?

If you don't intend to use them, a quick workaround would be to remove or move that files that define those back-ends, which would prevent company mode from trying to load them.

cd /location/of/company
mkdir unused-backends
mv company-semantic.* company-ropemacs.* company-pysmell.* unused-backends/

As long as you do not add unused-backends to your load-path, this will fix the problem.

If you want to use those backends (semantic is a parser for better context-appropriate emacs actions based on language, pysmell and ropemacs are both for usage with python), then installing them should fix this problem.