Lacking any indication of the problem except the error you pasted, I looked at the PoCo::Client::HTTP source on CPAN. Near line 1165, this is what I found (trimmed a bit for pasting):

sub _respond {
  my($heap, $request_id, $request) = @_;
  my $response = $request->[REQ_RESPONSE];
  if ($heap->{frmax}) {
    if ($heap->{redir}->{$request_id}->{followed}) {
      # ...
    }
    else {
      my $tmpresponse = $response;
      while (defined ...) {
        my $prev = $heap->{redir}->{$request_id}->{from};
        $tmpresponse->previous(...);
        $tmpresponse = $tmpresponse->previous();
        $request_id = $prev;
      }
    }
  }
  $request->[REQ_POSTBACK]->($response);
}
[download]

Assuming this is the same version you're using, or the line numbers are close enough that this is the code in question, it looks like previous is being called several times on $tmpresponse. This is a copy of $response, which in turn is a copy of $request->[REQ_RESPONSE].

Just guessing from that code, and the error you pasted, it looks like the response is undefined. The code should probably check for that possibility, but it doesn't appear to. Perhaps this is a bug that should be reported, but I'm just doing guesswork based on the scant evidence presented. :-)