Error extracting archive during automated WebAsyst update

When running automated WebAsyst update using WebAsyst Installer the following diagnostic message may appear in your browser:

2008.10.17 00:38:35:
/home/user/public_html/temp/updates/.webasyst_setup.tar.gz:
Extracted file /home/user/public_html/temp/updates/wbs.tgz does not have the correct
file size '' (9850105 expected).
Archive may be corrupted.

Such a message means that the update routine was unable to unpack the automatically downloaded archive file. There are several possible causes for that:

• The downloaded archive is corrupted. Restart the update routine which will re-download the archive from the WebAsyst update server.
• Missing sufficient free disc space for extracted files. Remove currently useless files from the server or extend your web hosting account to ensure the availability of more free disc space.