diff --git a/core/lib/Foswiki/Form/FieldDefinition.pm b/core/lib/Foswiki/Form/FieldDefinition.pm
index a203ec6835..13e6e20c21 100644
--- a/core/lib/Foswiki/Form/FieldDefinition.pm
+++ b/core/lib/Foswiki/Form/FieldDefinition.pm
@@ -239,7 +239,7 @@ sub populateMetaFromQueryData {
         if ( $this->isMultiValued() ) {
             my @values = $query->param( $this->{name} );
 
-            if ( scalar(@values) == 1 ) {
+            if ( scalar(@values) == 1 && defined $values[0] ) {
                 @values = split( /,|%2C/, $values[0] );
             }
             my %vset = ();
diff --git a/core/lib/Foswiki/OopsException.pm b/core/lib/Foswiki/OopsException.pm
index be8ce031ae..6a1ee2b208 100644
--- a/core/lib/Foswiki/OopsException.pm
+++ b/core/lib/Foswiki/OopsException.pm
@@ -181,7 +181,7 @@ sub stringify {
         if ( defined $this->{params} ) {
             $s .= ' params=>[' . join( ',', @{ $this->{params} } ) . ']';
         }
-        return $s . ')';
+        return $s . ')'.((DEBUG)?$this->stacktrace:'');
     }
 }