From 405412a24d7232162f61557a97d4091cd9830b6f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marius=20B=C4=82LTEANU?= <marius.balteanu@zitec.com>
Date: Fri, 2 Jan 2026 00:12:34 +0700
Subject: [PATCH] Fix RegexpError when validating CustomField with invalid
 regex and default value.


diff --git a/app/models/custom_field.rb b/app/models/custom_field.rb
index d14b67bdb..0eed2bf31 100644
--- a/app/models/custom_field.rb
+++ b/app/models/custom_field.rb
@@ -158,7 +158,7 @@ class CustomField < ApplicationRecord
       end
     end
 
-    if default_value.present?
+    if default_value.present? && errors[:regexp].blank?
       validate_field_value(default_value).each do |message|
         errors.add :default_value, message
       end
diff --git a/test/unit/custom_field_test.rb b/test/unit/custom_field_test.rb
index a6c8d35d3..121e865d1 100644
--- a/test/unit/custom_field_test.rb
+++ b/test/unit/custom_field_test.rb
@@ -48,6 +48,15 @@ class CustomFieldTest < ActiveSupport::TestCase
     assert field.save
   end
 
+  def test_regexp_validation_with_invalid_regex_and_default_value
+    field = IssueCustomField.new(:name => 'regexp', :field_format => 'text', :regexp => '[', :default_value => 'abc')
+    assert !field.save
+    assert_include I18n.t('activerecord.errors.messages.invalid'),
+                   field.errors[:regexp]
+    field.regexp = '[a-z0-9]'
+    assert field.save
+  end
+
   def test_default_value_should_be_validated
     field = CustomField.new(:name => 'Test', :field_format => 'int')
     field.default_value = 'abc'
-- 
2.50.1 (Apple Git-155)