FreeBSD portupgrade /usr/local/lib/ruby/site_ruby/1.8/portsdb.rb:567:in open_db: database file error

The portupgrade command is used to upgrade installed packages via ports or packages. This is one of the tool you need to use under FreeBSD. However, recently, it give me out following error on FreeBSD r6.2-p10-amd64 bit:
…
missing key: categories: Cannot read the portsdb!
/usr/local/lib/ruby/site_ruby/1.8/portsdb.rb:567:in `open_db’: database file error
….
The solution is pretty simple tp fix this error, enter:
# rm -f /usr/ports/INDEX*.db /var/db/pkg/pkgdb.db
# pkgdb -fu
# rm -rf /usr/ports
# portsnap fetch && portsnap extract && portsnap update
Next find out current portupgrade version:
# pkg_info | grep portupgrade
Sample output:

portupgrade-2.4.3_2,2 FreeBSD ports/packages administration and management tool s

# pkg_delete portupgrade-2.4.3_2,2
# cd /usr/ports/ports-mgmt/portupgrade && make clean && make install clean
# portupgrade -a

See /usr/ports/UPDATING file for more information.