Andrey

Problem:
An error appears during the update process.

Solution:
A reason can be an invalid site key and site URL.

Here's an outline of steps which help in the most of cases:

1. Generate a new site key (http://wpml.org/faq/install-wpml/)

2. Unregister WPML from your site. You can do this by clicking the Unregister button in Plugins >> Add New and navigate to "Commercial" section.

3. Register the site again from that place.

4. Finally, go to Dashboard >> Updates, choose WPML plugins for update and click on the update button.

Here's a video, which shows you the steps above:
http://screencast.com/t/59yTtuGTGFF

Leave a comment in this thread, if you still have the error "PCLZIP_ERR_BAD_FORMAT (-10) : Unable to find End of Central Dir Record signature".