Index: src/wp-admin/includes/class-wp-press-this.php
===================================================================
--- src/wp-admin/includes/class-wp-press-this.php	(revision 32121)
+++ src/wp-admin/includes/class-wp-press-this.php	(working copy)
@@ -1322,7 +1322,7 @@
 			<div class="alerts" role="alert" aria-live="assertive" aria-relevant="all" aria-atomic="true">
 				<?php
 
-				if ( empty( $data['v'] ) || $this->version > $data['v'] ) {
+				if ( isset( $data['v'] ) && $this->version > $data['v'] ) {
 					?>
 					<p class="alert is-notice">
 						<?php printf( __( 'You should upgrade <a href="%s" target="_blank">your bookmarklet</a> to the latest version!' ), admin_url( 'tools.php' ) ); ?>