portupgrade -arR errors

[Ilya Vishnyakov]

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Please help me to find out why portupgrade -arR gives me errors such as:

missing key: categories: Cannot read the portsdb!
/usr/local/lib/ruby/site_ruby/1.8/portsdb.rb:548:in `open_db':
database file error (PortsDB::DBError)
        from /usr/local/lib/ruby/site_ruby/1.8/portsdb.rb:702:in `port'
        from /usr/local/lib/ruby/site_ruby/1.8/portsdb.rb:890:in
`all_depends_list'
        from /usr/local/lib/ruby/site_ruby/1.8/pkgdb.rb:809:in
`tsort_build'
        from /usr/local/lib/ruby/site_ruby/1.8/pkgdb.rb:801:in `each'
        from /usr/local/lib/ruby/site_ruby/1.8/pkgdb.rb:801:in
`tsort_build'
        from /usr/local/lib/ruby/site_ruby/1.8/pkgdb.rb:823:in
`sort_build'
        from /usr/local/lib/ruby/site_ruby/1.8/pkgdb.rb:827:in
`sort_build!'
        from /usr/local/sbin/portupgrade:721:in `main'
        from /usr/local/lib/ruby/1.8/optparse.rb:755:in `initialize'
        from /usr/local/sbin/portupgrade:220:in `new'
        from /usr/local/sbin/portupgrade:220:in `main'
        from /usr/local/sbin/portupgrade:2084
However, I run  portsdb -Uu and it didn't show any errors.
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