That suggests it's hitting some duplicate entry prevention thing, like something with the same exact content being posted within some timeout window that I'm a little vague on.


*dives*

dw-free/cgi-bin/LJ/Protocol.pm

https://github.com/dreamwidth/dw-free/blob/346829d666d389c9e12eae7d1fa45134e0d42875/cgi-bin/LJ/Protocol.pm#L2320

        my $now = time();
        # broken client loop prevention
        if ($req->{'lastsync'}) {
            my $pname = "rl_syncitems_getevents_loop";
            # format is:  time/date/time/date/time/date/... so split
            # it into a hash, then delete pairs that are older than an hour
            my %reqs = split( m!/!, $u->prop( $pname ) );
            foreach (grep { $_ < $now - 60*60 } keys %reqs) { delete $reqs{$_}; }
            my $count = grep { $_ eq $date } values %reqs;
            $reqs{$now} = $date;
            if ($count >= 2) {
                # 2 prior, plus this one = 3 repeated requests for same synctime.
                # their client is busted.  (doesn't understand syncitems semantics)
                return fail($err,406);
            }

I hope this is helpful? I don't understand it fully, but that's where it's defined.