Sophos Anti-Virus: installation of package failed because of error during package decoding

Issue
Update reports that installation of package failed because of an error during package decoding.

You may see additional issues, including

Low disk space
Large number of files in the c:\windows\temp\sophos_autoupdate1.dir\ folder, typically can go to over 1GB in size. These can be safely deleted.
ALC log shows downloading to product cache as successful but the installation of, for example, Package Savxp fails ... (during package decoding).

Sophos Product and version
Sophos Anti-Virus

Operating system
Windows

What to do (pre Vista)

Delete the contents of
- C:\Program Files\Sophos\AutoUpdate\Cache
- C:\Program Files\Sophos\AutoUpdate\data\warehouse
Run the update again

If this fails, remove all Sophos components and reinstall them.

Delete the contents of
- C:\ProgramData\Sophos\AutoUpdate\Cache
- C:\ProgramData\Sophos\AutoUpdate\data\warehouse
Run the update again

If this fails, remove all Sophos components and reinstall them.

If you need more information or guidance, then please contact technical support.