diff --git a/lib/NGCP/Panel/Role/API.pm b/lib/NGCP/Panel/Role/API.pm
index 41fb429b7d..fc1b09ddda 100644
--- a/lib/NGCP/Panel/Role/API.pm
+++ b/lib/NGCP/Panel/Role/API.pm
@@ -100,10 +100,10 @@ sub validate_form {
             if $resource->{$k}->$_isa('DateTime');
         $resource->{$k} = $resource->{$k} + 0
             if(defined $resource->{$k} && (
-               $resource->{$k}->is_int || $resource->{$k}->is_decimal) && (
                $form->field($k)->$_isa('HTML::FormHandler::Field::Integer') ||
                $form->field($k)->$_isa('HTML::FormHandler::Field::Money') ||
-               $form->field($k)->$_isa('HTML::FormHandler::Field::Float')));
+               $form->field($k)->$_isa('HTML::FormHandler::Field::Float')) &&
+               ($resource->{$k}->is_int || $resource->{$k}->is_decimal));
 
         # only do this for converting back from obj to hal
         # otherwise it breaks db fields with the \0 and \1 notation
@@ -192,10 +192,11 @@ sub valid_precondition {
 
 sub require_preference {
     my ($self, $c) = @_;
+    return 'minimal' unless $c->request->header('Prefer');
     my @preference = grep { 'return' eq $_->[0] } split_header_words($c->request->header('Prefer'));
     return $preference[0][1]
         if 1 == @preference && ('minimal' eq $preference[0][1] || 'representation' eq $preference[0][1]);
-    return 'minimal';
+    $self->error($c, HTTP_BAD_REQUEST, "Header 'Prefer' must be either 'return=minimal' or 'return=representation'.");
 }
 
 sub require_wellformed_json {
diff --git a/t/api-billingfees.t b/t/api-billingfees.t
index 3bf43ed25f..a58f844cc6 100644
--- a/t/api-billingfees.t
+++ b/t/api-billingfees.t
@@ -351,7 +351,7 @@ my @allfees = ();
     delete $fee->{_links};
     delete $fee->{_embedded};
     $req = HTTP::Request->new('PUT', $uri.'/'.$firstfee);
-    
+
     # check if it fails without content type
     $req->remove_header('Content-Type');
     $req->header('Prefer' => "return=minimal");
@@ -366,17 +366,11 @@ my @allfees = ();
     $req->remove_header('Content-Type');
     $req->header('Content-Type' => 'application/json');
 
-    # check if it fails with missing Prefer
-    $req->remove_header('Prefer');
-    $res = $ua->request($req);
-    is($res->code, 400, "check put missing prefer");
-
     # check if it fails with invalid Prefer
     $req->header('Prefer' => "return=invalid");
     $res = $ua->request($req);
     is($res->code, 400, "check put invalid prefer");
 
-
     $req->remove_header('Prefer');
     $req->header('Prefer' => "return=representation");
 
diff --git a/t/api-billingprofiles.t b/t/api-billingprofiles.t
index d45699e696..a3a8b6de02 100644
--- a/t/api-billingprofiles.t
+++ b/t/api-billingprofiles.t
@@ -205,11 +205,6 @@ my @allprofiles = ();
     $req->remove_header('Content-Type');
     $req->header('Content-Type' => 'application/json');
 
-    # check if it fails with missing Prefer
-    $req->remove_header('Prefer');
-    $res = $ua->request($req);
-    is($res->code, 400, "check put missing prefer");
-
     # check if it fails with invalid Prefer
     $req->header('Prefer' => "return=invalid");
     $res = $ua->request($req);
diff --git a/t/api-contracts.t b/t/api-contracts.t
index cf10628259..93d7dba08b 100644
--- a/t/api-contracts.t
+++ b/t/api-contracts.t
@@ -271,17 +271,11 @@ my @allcontracts = ();
     $req->remove_header('Content-Type');
     $req->header('Content-Type' => 'application/json');
 
-    # check if it fails with missing Prefer
-    $req->remove_header('Prefer');
-    $res = $ua->request($req);
-    is($res->code, 400, "check put missing prefer");
-
     # check if it fails with invalid Prefer
     $req->header('Prefer' => "return=invalid");
     $res = $ua->request($req);
     is($res->code, 400, "check put invalid prefer");
 
-
     $req->remove_header('Prefer');
     $req->header('Prefer' => "return=representation");
 
diff --git a/t/api-customercontacts.t b/t/api-customercontacts.t
index 08f18cb74a..eaf0fd3f53 100644
--- a/t/api-customercontacts.t
+++ b/t/api-customercontacts.t
@@ -207,11 +207,6 @@ my @allcontacts = ();
     $req->remove_header('Content-Type');
     $req->header('Content-Type' => 'application/json');
 
-    # check if it fails with missing Prefer
-    $req->remove_header('Prefer');
-    $res = $ua->request($req);
-    is($res->code, 400, "check put missing prefer");
-
     # check if it fails with invalid Prefer
     $req->header('Prefer' => "return=invalid");
     $res = $ua->request($req);
diff --git a/t/api-customers.t b/t/api-customers.t
index 9ce0aee712..24bfadff7c 100644
--- a/t/api-customers.t
+++ b/t/api-customers.t
@@ -305,17 +305,11 @@ my @allcustomers = ();
     $req->remove_header('Content-Type');
     $req->header('Content-Type' => 'application/json');
 
-    # check if it fails with missing Prefer
-    $req->remove_header('Prefer');
-    $res = $ua->request($req);
-    is($res->code, 400, "check put missing prefer");
-
     # check if it fails with invalid Prefer
     $req->header('Prefer' => "return=invalid");
     $res = $ua->request($req);
     is($res->code, 400, "check put invalid prefer");
 
-
     $req->remove_header('Prefer');
     $req->header('Prefer' => "return=representation");
 
diff --git a/t/api-resellers.t b/t/api-resellers.t
index 25aafbc9d5..717a200889 100644
--- a/t/api-resellers.t
+++ b/t/api-resellers.t
@@ -279,7 +279,7 @@ my @allresellers = ();
     delete $reseller->{_links};
     delete $reseller->{_embedded};
     $req = HTTP::Request->new('PUT', $uri.'/'.$firstreseller);
-    
+
     # check if it fails without content type
     $req->remove_header('Content-Type');
     $req->header('Prefer' => "return=minimal");
@@ -294,11 +294,6 @@ my @allresellers = ();
     $req->remove_header('Content-Type');
     $req->header('Content-Type' => 'application/json');
 
-    # check if it fails with missing Prefer
-    $req->remove_header('Prefer');
-    $res = $ua->request($req);
-    is($res->code, 400, "check put missing prefer");
-
     # check if it fails with invalid Prefer
     $req->header('Prefer' => "return=invalid");
     $res = $ua->request($req);
diff --git a/t/api-rewriterulesets.t b/t/api-rewriterulesets.t
index 19b6532e1d..7147ad68a7 100644
--- a/t/api-rewriterulesets.t
+++ b/t/api-rewriterulesets.t
@@ -304,17 +304,11 @@ my @allrules = ();
     $req->remove_header('Content-Type');
     $req->header('Content-Type' => 'application/json');
 
-    # check if it fails with missing Prefer
-    $req->remove_header('Prefer');
-    $res = $ua->request($req);
-    is($res->code, 400, "check put missing prefer");
-
     # check if it fails with invalid Prefer
     $req->header('Prefer' => "return=invalid");
     $res = $ua->request($req);
     is($res->code, 400, "check put invalid prefer");
 
-
     $req->remove_header('Prefer');
     $req->header('Prefer' => "return=representation");
 
diff --git a/t/api-systemcontacts.t b/t/api-systemcontacts.t
index b944c14e49..f8e960e9af 100644
--- a/t/api-systemcontacts.t
+++ b/t/api-systemcontacts.t
@@ -154,7 +154,7 @@ my @allcontacts = ();
     delete $contact->{_embedded};
     $req = HTTP::Request->new('PUT', $uri.'/'.$firstcontact);
     $req->header('Prefer' => 'return=minimal');
-    
+
     # check if it fails without content type
     $req->remove_header('Content-Type');
     $res = $ua->request($req);
@@ -168,17 +168,11 @@ my @allcontacts = ();
     $req->remove_header('Content-Type');
     $req->header('Content-Type' => 'application/json');
 
-    # check if it fails with missing Prefer
-    $req->remove_header('Prefer');
-    $res = $ua->request($req);
-    is($res->code, 400, "check put missing prefer");
-
     # check if it fails with invalid Prefer
     $req->header('Prefer' => "return=invalid");
     $res = $ua->request($req);
     is($res->code, 400, "check put invalid prefer");
 
-
     $req->remove_header('Prefer');
     $req->header('Prefer' => "return=representation");
 
diff --git a/t/api-valid-patch.t b/t/api-valid-patch.t
index f615a69466..e4ea4255d6 100644
--- a/t/api-valid-patch.t
+++ b/t/api-valid-patch.t
@@ -24,11 +24,6 @@ $ua->ssl_opts(
 {
     $req = HTTP::Request->new('PATCH', $uri.'/api/systemcontacts/1');
 
-    $res = $ua->request($req);
-    is($res->code, 400, "check patch missing Prefer code");
-    $body = JSON::from_json($res->decoded_content);
-    ok($body->{message} =~ /Use the 'Prefer' header/, "check patch missing Prefer response");
-
     $req->header('Prefer' => 'return=minimal');
     $res = $ua->request($req);
     is($res->code, 415, "check patch missing media type");
@@ -43,7 +38,7 @@ $ua->ssl_opts(
     $res = $ua->request($req);
     is($res->code, 400, "check patch missing body");
     $body = JSON::from_json($res->decoded_content);
-    ok($body->{message} =~ /is missing a message body/, "check patch missing body response");
+    like($body->{message}, qr/is missing a message body/, "check patch missing body response");
 
     $req->content(JSON::to_json(
         { foo => 'bar' },
@@ -51,7 +46,7 @@ $ua->ssl_opts(
     $res = $ua->request($req);
     is($res->code, 400, "check patch no array body");
     $body = JSON::from_json($res->decoded_content);
-    ok($body->{message} =~ /must be an array/, "check patch missing body response");
+    like($body->{message}, qr/must be an array/, "check patch missing body response");
     
     $req->content(JSON::to_json(
         [{ foo => 'bar' }],
@@ -59,7 +54,7 @@ $ua->ssl_opts(
     $res = $ua->request($req);
     is($res->code, 400, "check patch no op in body");
     $body = JSON::from_json($res->decoded_content);
-    ok($body->{message} =~ /must have an 'op' field/, "check patch no op in body response");
+    like($body->{message}, qr/must have an 'op' field/, "check patch no op in body response");
 
     $req->content(JSON::to_json(
         [{ op => 'bar' }],
@@ -67,23 +62,23 @@ $ua->ssl_opts(
     $res = $ua->request($req);
     is($res->code, 400, "check patch invalid op in body");
     $body = JSON::from_json($res->decoded_content);
-    ok($body->{message} =~ /Invalid PATCH op /, "check patch no op in body response");
+    like($body->{message}, qr/Invalid PATCH op /, "check patch no op in body response");
 
     $req->content(JSON::to_json(
-        [{ op => 'test' }],
+        [{ op => 'replace' }],
     ));
     $res = $ua->request($req);
     is($res->code, 400, "check patch missing fields for op");
     $body = JSON::from_json($res->decoded_content);
-    ok($body->{message} =~ /Missing PATCH keys /, "check patch missing fields for op response");
+    like($body->{message}, qr/Missing PATCH keys /, "check patch missing fields for op response");
 
     $req->content(JSON::to_json(
-        [{ op => 'test', path => '/foo', value => 'bar', invalid => 'sna' }],
+        [{ op => 'replace', path => '/foo', value => 'bar', invalid => 'sna' }],
     ));
     $res = $ua->request($req);
     is($res->code, 400, "check patch extra fields for op");
     $body = JSON::from_json($res->decoded_content);
-    ok($body->{message} =~ /Invalid PATCH key /, "check patch extra fields for op response");
+    like($body->{message}, qr/Invalid PATCH key /, "check patch extra fields for op response");
 }
 
 done_testing;