(#2122) CiviEvent - Pre-upgrade warning

CRM/Upgrade/Incremental/php/FiveFortySeven.php

@@ -33,6 +33,14 @@ class CRM_Upgrade_Incremental_php_FiveFortySeven extends CRM_Upgrade_Incremental
    * @param null $currentVer
    */
   public function setPreUpgradeMessage(&$preUpgradeMessage, $rev, $currentVer = NULL): void {
+    if ($rev === '5.47.alpha1' && version_compare($currentVer, '5.47', '<')) {
+      // Note: This warning should only exist within a few patch releases of 5.47. Do not merge-forward.
+      $prose = ts('<strong>CiviEvent users may have migration problems with v%1.</strong> CiviEvent users should consider v5.46 instead. <a %2>More information</a>', [
+        1 => CRM_Utils_System::version(),
+        2 => 'target="_blank" href="https://civicrm.org/redirect/event-timezone-5.47"',
+      ]);
+      $preUpgradeMessage = '<p>' . $prose . '</p>' . $preUpgradeMessage;
+    }
     if ($rev === '5.47.alpha1') {
       $count = CRM_Core_DAO::singleValueQuery('SELECT count(*) FROM civicrm_contact WHERE preferred_mail_format != "Both"');
       if ($count) {