After migrating awstats data from debian i386 to debian amd64, awstat gives me the following error:

/usr/lib/cgi-bin/awstats.pl -config=awstats -update
Update for config "/etc/awstats/awstats.conf"
With data in log file "/var/log/apache2/access.log"...
Warning: Error while retrieving hashfile: Byte order is not compatible at 
../../lib/Storable.pm (autosplit into ../../lib/auto/Storable/_retrieve.al) 
line 331, at (eval 5) line 1

Explanation is here : hashes are not stored in the same way by Perl Storable on debian 32 bit and 64 bit.
The workaround is pretty simple: delete all hashes files, awstats will rebuild them

rm /var/lib/awstats/*.hash