diff -r 7b1b88e27a20 -r 48c4eec2b7e6 wp/wp-admin/widgets-form-blocks.php
--- a/wp/wp-admin/widgets-form-blocks.php	Thu Sep 29 08:06:27 2022 +0200
+++ b/wp/wp-admin/widgets-form-blocks.php	Fri Sep 05 18:40:08 2025 +0200
@@ -73,7 +73,50 @@
 do_action( 'widgets_admin_page' );
 ?>
 
-<div id="widgets-editor" class="blocks-widgets-container"></div>
+<div id="widgets-editor" class="blocks-widgets-container">
+	<?php // JavaScript is disabled. ?>
+	<div class="wrap hide-if-js widgets-editor-no-js">
+		<h1 class="wp-heading-inline"><?php echo esc_html( $title ); ?></h1>
+		<?php
+		if ( file_exists( WP_PLUGIN_DIR . '/classic-widgets/classic-widgets.php' ) ) {
+			// If Classic Widgets is already installed, provide a link to activate the plugin.
+			$installed           = true;
+			$plugin_activate_url = wp_nonce_url( 'plugins.php?action=activate&amp;plugin=classic-widgets/classic-widgets.php', 'activate-plugin_classic-widgets/classic-widgets.php' );
+			$message             = sprintf(
+				/* translators: %s: Link to activate the Classic Widgets plugin. */
+				__( 'The block widgets require JavaScript. Please enable JavaScript in your browser settings, or activate the <a href="%s">Classic Widgets plugin</a>.' ),
+				esc_url( $plugin_activate_url )
+			);
+		} else {
+			// If Classic Widgets is not installed, provide a link to install it.
+			$installed          = false;
+			$plugin_install_url = wp_nonce_url( self_admin_url( 'update.php?action=install-plugin&plugin=classic-widgets' ), 'install-plugin_classic-widgets' );
+			$message            = sprintf(
+				/* translators: %s: A link to install the Classic Widgets plugin. */
+				__( 'The block widgets require JavaScript. Please enable JavaScript in your browser settings, or install the <a href="%s">Classic Widgets plugin</a>.' ),
+				esc_url( $plugin_install_url )
+			);
+		}
+		/**
+		 * Filters the message displayed in the block widget interface when JavaScript is
+		 * not enabled in the browser.
+		 *
+		 * @since 6.4.0
+		 *
+		 * @param string $message The message being displayed.
+		 * @param bool   $installed Whether the Classic Widget plugin is installed.
+		 */
+		$message = apply_filters( 'block_widgets_no_javascript_message', $message, $installed );
+		wp_admin_notice(
+			$message,
+			array(
+				'type'               => 'error',
+				'additional_classes' => array( 'hide-if-js' ),
+			)
+		);
+		?>
+	</div>
+</div>
 
 <?php
 /** This action is documented in wp-admin/widgets-form.php */