Comment 1 for bug 1500557

apport will not check Launchpad for a package that it does not find in the package cache from packaging-apt-dpkg.py we have:

try:
    dbgsym_pkg = pkg + '-dbgsym'
    dbgsym = cache[dbgsym_pkg]
    ....
except KeyError:
     obsolete += 'no debug symbol package found for %s\n' % pkg

So because the Packages file is out of date / incorrect apport-retrace is running into issues.