Index: src/wp-admin/js/updates.js
===================================================================
--- src/wp-admin/js/updates.js	(revision 40994)
+++ src/wp-admin/js/updates.js	(working copy)
@@ -2053,6 +2053,9 @@
 			wp.updates.maybeRequestFilesystemCredentials( event );
 
 			event.preventDefault();
+			
+			// Disable the Apply button while working
+			$(this).prop( 'disabled', true );
 
 			// Un-check the bulk checkboxes.
 			$bulkActionForm.find( '.manage-column [type="checkbox"]' ).prop( 'checked', false );
@@ -2084,6 +2087,7 @@
 
 			// Display bulk notification for updates of any kind.
 			$document.on( 'wp-plugin-update-success wp-plugin-update-error wp-theme-update-success wp-theme-update-error', function( event, response ) {
+				
 				var $itemRow = $( '[data-slug="' + response.slug + '"]' ),
 					$bulkActionNotice, itemName;
 
@@ -2121,6 +2125,9 @@
 				if ( error > 0 && ! wp.updates.queue.length ) {
 					$( 'html, body' ).animate( { scrollTop: 0 } );
 				}
+				
+				// Re-enable the Apply button after displaying update notifications
+				$bulkActionForm.find( 'input[type="submit"]' ).prop( 'disabled', false );
 			} );
 
 			// Reset admin notice template after #bulk-action-notice was added.