diff --git a/lib/class-experimental-wp-widget-blocks-manager.php b/lib/class-experimental-wp-widget-blocks-manager.php
index 8f124305bf609..c915807bd769b 100644
--- a/lib/class-experimental-wp-widget-blocks-manager.php
+++ b/lib/class-experimental-wp-widget-blocks-manager.php
@@ -126,8 +126,8 @@ public static function get_sidebar_as_blocks( $sidebar_id ) {
 			$new_block               = array(
 				'blockName' => 'core/legacy-widget',
 				'attrs'     => array(
-					'widgetId'    => $item,
-					'instance'    => self::get_sidebar_widget_instance( $wp_registered_sidebars[ $sidebar_id ], $item ),
+					'id'       => $item,
+					'instance' => self::get_sidebar_widget_instance( $wp_registered_sidebars[ $sidebar_id ], $item ),
 				),
 				'innerHTML' => '',
 			);
@@ -138,7 +138,7 @@ public static function get_sidebar_as_blocks( $sidebar_id ) {
 				$new_block['attrs']['idBase'] = $object->id_base;
 			}
 			if ( is_int( $number ) ) {
-				$new_block['attrs']['widgetNumber'] = $number;
+				$new_block['attrs']['number'] = $number;
 			}
 			$blocks[] = $new_block;
 		}
diff --git a/lib/class-wp-rest-widget-forms.php b/lib/class-wp-rest-widget-forms.php
index ed59f6f8ddc73..c2f7299b557e0 100644
--- a/lib/class-wp-rest-widget-forms.php
+++ b/lib/class-wp-rest-widget-forms.php
@@ -96,7 +96,7 @@ public function compute_new_widget_permissions_check() {
 	 * @return boolean| True if the widget being referenced exists and false otherwise.
 	 */
 	private function is_valid_widget( $widget_class ) {
-		global $wp_widget_factory, $wp_registered_widgets;
+		global $wp_widget_factory;
 		if ( ! $widget_class ) {
 			return false;
 		}
diff --git a/packages/block-library/src/legacy-widget/edit/dom-manager.js b/packages/block-library/src/legacy-widget/edit/dom-manager.js
index 1d6586f24c277..ccabc4408f066 100644
--- a/packages/block-library/src/legacy-widget/edit/dom-manager.js
+++ b/packages/block-library/src/legacy-widget/edit/dom-manager.js
@@ -36,8 +36,8 @@ class LegacyWidgetEditDomManager extends Component {
 			this.idBaseInputRef.current.value = nextProps.idBase;
 			shouldTriggerWidgetUpdateEvent = true;
 		}
-		if ( nextProps.widgetNumber !== this.props.widgetNumber && this.widgetNumberInputRef.current ) {
-			this.widgetNumberInputRef.current.value = nextProps.widgetNumber;
+		if ( nextProps.number !== this.props.number && this.widgetNumberInputRef.current ) {
+			this.widgetNumberInputRef.current.value = nextProps.number;
 		}
 		if ( nextProps.form !== this.props.form && this.widgetContentRef.current ) {
 			const widgetContent = this.widgetContentRef.current;
@@ -54,7 +54,7 @@ class LegacyWidgetEditDomManager extends Component {
 	}
 
 	render() {
-		const { id, idBase, widgetNumber, form, isReferenceWidget } = this.props;
+		const { id, idBase, number, form, isReferenceWidget } = this.props;
 		return (
 			<div className="widget open" ref={ this.containerRef }>
 				<div className="widget-inside">
@@ -79,12 +79,15 @@ class LegacyWidgetEditDomManager extends Component {
 							className="widget-content"
 							dangerouslySetInnerHTML={ { __html: form } }
 						/>
-						{ isReferenceWidget && ( <><input type="hidden" name="widget-id" className="widget-id" value={ id } />
-							<input ref={ this.idBaseInputRef } type="hidden" name="id_base" className="id_base" value={ idBase } />
-							<input ref={ this.widgetNumberInputRef } type="hidden" name="widget_number" className="widget_number" value={ widgetNumber } />
-							<input type="hidden" name="multi_number" className="multi_number" value="" />
-							<input type="hidden" name="add_new" className="add_new" value="" />
-						</> ) }
+						{ isReferenceWidget && (
+							<>
+								<input type="hidden" name="widget-id" className="widget-id" value={ id } />
+								<input ref={ this.idBaseInputRef } type="hidden" name="id_base" className="id_base" value={ idBase } />
+								<input ref={ this.widgetNumberInputRef } type="hidden" name="widget_number" className="widget_number" value={ number } />
+								<input type="hidden" name="multi_number" className="multi_number" value="" />
+								<input type="hidden" name="add_new" className="add_new" value="" />
+							</>
+						) }
 					</form>
 				</div>
 			</div>
diff --git a/packages/block-library/src/legacy-widget/edit/handler.js b/packages/block-library/src/legacy-widget/edit/handler.js
index 97cb024ffb45c..96983ffac1bf2 100644
--- a/packages/block-library/src/legacy-widget/edit/handler.js
+++ b/packages/block-library/src/legacy-widget/edit/handler.js
@@ -59,7 +59,7 @@ class LegacyWidgetEditHandler extends Component {
 	}
 
 	render() {
-		const { instanceId, widgetId, widgetNumber, idBase, instance, isSelected, widgetName } = this.props;
+		const { instanceId, id, number, idBase, instance, isSelected, widgetName } = this.props;
 		const { form } = this.state;
 
 		if ( ! form ) {
@@ -96,16 +96,15 @@ class LegacyWidgetEditHandler extends Component {
 				>
 
 					<LegacyWidgetEditDomManager
-						isReferenceWidget={ !! widgetId }
+						isReferenceWidget={ !! id }
 						ref={ ( ref ) => {
 							this.widgetEditDomManagerRef = ref;
 						} }
 						onInstanceChange={ this.onInstanceChange }
-						widgetNumber={ widgetNumber ? widgetNumber : instanceId * -1 }
-						id={ widgetId }
+						number={ number ? number : instanceId * -1 }
+						id={ id }
 						idBase={ idBase }
 						form={ form }
-						widgetId={ widgetId }
 					/>
 				</div>
 			</>
@@ -120,8 +119,8 @@ class LegacyWidgetEditHandler extends Component {
 	}
 
 	onInstanceChange( instanceChanges ) {
-		const { widgetId } = this.props;
-		if ( widgetId ) {
+		const { id } = this.props;
+		if ( id ) {
 			// For reference widgets there is no need to query an endpoint,
 			// the widget is already saved with ajax.
 			this.props.onInstanceChange( instanceChanges, true );
@@ -134,29 +133,28 @@ class LegacyWidgetEditHandler extends Component {
 	}
 
 	requestWidgetUpdater( instanceChanges, callback ) {
-		const { widgetId, idBase, instance, widgetClass } = this.props;
+		const { id, idBase, instance, widgetClass } = this.props;
 		const { isStillMounted } = this;
-		if ( ! widgetId && ! widgetClass ) {
+		if ( ! id && ! widgetClass ) {
 			return;
 		}
 
 		// If we are in the presence of a reference widget, do a save ajax request
 		// with empty changes so we retrieve the widget edit form.
-		if ( widgetId ) {
+		if ( id ) {
 			const httpRequest = new XMLHttpRequest();
 			const formData = new FormData();
 			formData.append( 'action', 'save-widget' );
 			formData.append( 'id_base', idBase );
-			formData.append( 'widget-id', widgetId );
+			formData.append( 'widget-id', id );
 			formData.append( 'widget-width', '250' );
 			formData.append( 'widget-height', '200' );
 			formData.append( 'savewidgets', this.widgetNonce );
 			httpRequest.open( 'POST', window.ajaxurl );
-			const self = this;
-			httpRequest.addEventListener( 'load', function() {
+			httpRequest.addEventListener( 'load', () => {
 				if ( isStillMounted ) {
 					const form = httpRequest.responseText;
-					self.setState( { form } );
+					this.setState( { form } );
 					if ( callback ) {
 						callback( { form } );
 					}
diff --git a/packages/block-library/src/legacy-widget/edit/index.js b/packages/block-library/src/legacy-widget/edit/index.js
index e2c960080c011..3387640fefe87 100644
--- a/packages/block-library/src/legacy-widget/edit/index.js
+++ b/packages/block-library/src/legacy-widget/edit/index.js
@@ -48,21 +48,20 @@ class LegacyWidgetEdit extends Component {
 			setAttributes,
 		} = this.props;
 		const { isPreview, hasEditForm } = this.state;
-		const { widgetId, widgetClass } = attributes;
+		const { id, widgetClass } = attributes;
 		const widgetObject =
-			( widgetId && availableLegacyWidgets[ widgetId ] ) ||
+			( id && availableLegacyWidgets[ id ] ) ||
 			( widgetClass && availableLegacyWidgets[ widgetClass ] );
-		if ( ! widgetId && ! widgetClass ) {
+		if ( ! id && ! widgetClass ) {
 			return (
 				<LegacyWidgetPlaceholder
 					availableLegacyWidgets={ availableLegacyWidgets }
-					currentWidget={ widgetId }
 					hasPermissionsToManageWidgets={ hasPermissionsToManageWidgets }
 					onChangeWidget={ ( newWidget ) => {
 						const { isReferenceWidget } = availableLegacyWidgets[ newWidget ];
 						setAttributes( {
 							instance: {},
-							widgetId: isReferenceWidget ? newWidget : undefined,
+							id: isReferenceWidget ? newWidget : undefined,
 							widgetClass: isReferenceWidget ? undefined : newWidget,
 						} );
 					} }
@@ -120,9 +119,9 @@ class LegacyWidgetEdit extends Component {
 					<LegacyWidgetEditHandler
 						isSelected={ isSelected }
 						isVisible={ ! isPreview }
-						widgetId={ attributes.widgetId }
-						idBase={ attributes.idBase || attributes.widgetId }
-						widgetNumber={ attributes.widgetNumber }
+						id={ id }
+						idBase={ attributes.idBase || attributes.id }
+						number={ attributes.number }
 						widgetName={ get( widgetObject, [ 'name' ] ) }
 						widgetClass={ attributes.widgetClass }
 						instance={ attributes.instance }
@@ -151,7 +150,7 @@ class LegacyWidgetEdit extends Component {
 		this.switchToEdit();
 		this.props.setAttributes( {
 			instance: {},
-			widgetId: undefined,
+			id: undefined,
 			widgetClass: undefined,
 		} );
 		this.setState( {
diff --git a/packages/block-library/src/legacy-widget/index.php b/packages/block-library/src/legacy-widget/index.php
index 1ef68398624e0..d0a91f3f6c619 100644
--- a/packages/block-library/src/legacy-widget/index.php
+++ b/packages/block-library/src/legacy-widget/index.php
@@ -72,17 +72,17 @@ function render_widget_by_id( $id ) {
  * @return string Returns the post content with the legacy widget added.
  */
 function render_block_legacy_widget( $attributes ) {
-	$widget_id    = null;
+	$id           = null;
 	$widget_class = null;
-	if ( isset( $attributes['widgetId'] ) ) {
-		$widget_id = $attributes['widgetId'];
+	if ( isset( $attributes['id'] ) ) {
+		$id = $attributes['id'];
 	}
 	if ( isset( $attributes['widgetClass'] ) ) {
 		$widget_class = $attributes['widgetClass'];
 	}
 
-	if ( $widget_id ) {
-		return render_widget_by_id( $widget_id );
+	if ( $id ) {
+		return render_widget_by_id( $id );
 	}
 	if ( ! $widget_class ) {
 		return '';
@@ -105,19 +105,19 @@ function register_block_core_legacy_widget() {
 		'core/legacy-widget',
 		array(
 			'attributes'      => array(
-				'widgetClass'  => array(
+				'widgetClass' => array(
 					'type' => 'string',
 				),
-				'widgetId'     => array(
+				'id'          => array(
 					'type' => 'string',
 				),
-				'idBase'       => array(
+				'idBase'      => array(
 					'type' => 'string',
 				),
-				'widgetNumber' => array(
+				'number'      => array(
 					'type' => 'number',
 				),
-				'instance'     => array(
+				'instance'    => array(
 					'type' => 'object',
 				),
 			),