# connect to mongo
mongo -u admin2 admin -p
use iprace
# find all damaged documents
db.getCollection('seedlist_url').find({'url' : { $exists : false }});
> { "_id" : ObjectId("58905990b1a1fc4a564a8370"), "class" : "iPrace_superkarieracz" }
# delete all affected documents by _id
db.getCollection('seedlist_url').remove({ "_id" : ObjectId('58905990b1a1fc4a564a8370')});
# exit database cli
# reboot failed crawler daemon
# name of the daemon can be found in /etc/supervisor/conf.d/iprace.conf (after program:)
supervisorctl restart iprace-superkariera-daemon: