Failed to exec method /usr/lib/apt/methods/

Error message:

# apt-get update
Failed to exec method /usr/lib/apt/methods/
Failed to exec method /usr/lib/apt/methods/
E: Method has died unexpectedly!
E: Sub-process returned an error code (100)
E: Method /usr/lib/apt/methods/ did not start correctly
E: Method has died unexpectedly!
E: Sub-process returned an error code (100)
E: Method /usr/lib/apt/methods/ did not start correctly

How to resolve a problem (check sources):

# vim /etc/apt/sources.list

(replace) deb ://..
(with) deb http://

or check other sources..