diff --git a/mozilla/webtools/testopia/extensions/testopia/lib/Testopia/Search.pm b/mozilla/webtools/testopia/extensions/testopia/lib/Testopia/Search.pm
index 07e8d399941..498d8f2a43e 100644
--- a/mozilla/webtools/testopia/extensions/testopia/lib/Testopia/Search.pm
+++ b/mozilla/webtools/testopia/extensions/testopia/lib/Testopia/Search.pm
@@ -1428,6 +1428,7 @@ sub init {
     foreach my $profile ("author", "manager", "default_tester", 
                          "assignee", "testedby"){
         $t = $cgi->param($profile . "_type") || '';
+        $t = "isnull" if ($cgi->param($profile) eq '--unassigned--');
         if ($t eq "exact"  || $t eq '') {
             $t = "anyexact";
             if ($cgi->param($profile)){
diff --git a/mozilla/webtools/testopia/extensions/testopia/lib/Testopia/TestCaseRun.pm b/mozilla/webtools/testopia/extensions/testopia/lib/Testopia/TestCaseRun.pm
index 12e8b4a4d10..62be831f4c7 100644
--- a/mozilla/webtools/testopia/extensions/testopia/lib/Testopia/TestCaseRun.pm
+++ b/mozilla/webtools/testopia/extensions/testopia/lib/Testopia/TestCaseRun.pm
@@ -516,13 +516,14 @@ sub set_assignee {
     my ($user_id) = @_;
 
     my $assignee = $self->_check_assignee($user_id);
-    my $oldassignee = $self->assignee->login;
+    my $oldassignee = $self->assignee->login || '--unassigned--';
     my $newassignee = Bugzilla::User->new($assignee);
+    my $newassignee_name = $newassignee->id ? $newassignee->login : '--unassigned--';
     
     $self->_update_fields({'assignee' => $assignee});
     $self->{'assignee'} = $assignee;
     
-    my $note = "Assignee changed from $oldassignee to ". $newassignee->login;
+    my $note = "Assignee changed from $oldassignee to ". $newassignee_name;
     $note   .= " by ". Bugzilla->user->login;
     $note   .= " for build '". $self->build->name;
     $note   .= "' and environment '". $self->environment->name;
diff --git a/mozilla/webtools/testopia/tr_caserun.cgi b/mozilla/webtools/testopia/tr_caserun.cgi
index 6ab8493fa49..3c31ccb7843 100755
--- a/mozilla/webtools/testopia/tr_caserun.cgi
+++ b/mozilla/webtools/testopia/tr_caserun.cgi
@@ -113,8 +113,10 @@ elsif ($action eq 'update_note'){
 elsif ($action eq 'update_assignee'){
     print $cgi->header;
     ThrowUserError("testopia-read-only", {'object' => $caserun}) unless $caserun->canedit;
-    
-    my $assignee_id = login_to_id(trim($cgi->param('assignee')),'THROW_ERROR');
+    my $assignee_id;
+    if ($cgi->param('assignee')){
+        $assignee_id = login_to_id(trim($cgi->param('assignee')),'THROW_ERROR');
+    }
 
     $caserun->set_assignee($assignee_id);