From 5184f1b679ecd4ba8483664c6f0add8f9bf204bf Mon Sep 17 00:00:00 2001
From: Rich Lott / Artful Robot <forums@artfulrobot.uk>
Date: Tue, 26 May 2020 15:29:26 +0100
Subject: [PATCH] Fix core#1773 unsubscribe form causes errors if submitted
 twice

---
 CRM/Mailing/Form/Unsubscribe.php | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/CRM/Mailing/Form/Unsubscribe.php b/CRM/Mailing/Form/Unsubscribe.php
index 4f2c4f7874..95a6759659 100644
--- a/CRM/Mailing/Form/Unsubscribe.php
+++ b/CRM/Mailing/Form/Unsubscribe.php
@@ -16,6 +16,14 @@
  */
 class CRM_Mailing_Form_Unsubscribe extends CRM_Core_Form {
 
+  /**
+   * Prevent people double-submitting the form (e.g. by double-clicking).
+   * https://lab.civicrm.org/dev/core/-/issues/1773
+   *
+   * @var bool
+   */
+  public $submitOnce = TRUE;
+
   public function preProcess() {
 
     $this->_type = 'unsubscribe';
-- 
2.25.1