Ticket #48964: 48964.patch

src/wp-includes/class-wp-fatal-error-handler.php

@@ -30 +30 @@
                         return;
                 }
 
+                // Do not trigger the fatal error handler while upgrades are being installed.
+                if ( wp_in_maintenance_mode() ) {
+                        return;
+                }
+
                 try {
                         // Bail if no error found.
                         $error = $this->detect_error();