diff --git a/packages/core-compat-api/src/collectLegacyRoutes.test.tsx b/packages/core-compat-api/src/collectLegacyRoutes.test.tsx
index 4c2acd35a6..0319628b14 100644
--- a/packages/core-compat-api/src/collectLegacyRoutes.test.tsx
+++ b/packages/core-compat-api/src/collectLegacyRoutes.test.tsx
@@ -73,7 +73,7 @@ describe('collectLegacyRoutes', () => {
             defaultConfig: {},
           },
           {
-            id: 'api:plugin.scoringdata.service',
+            id: 'api:score-card/plugin.scoringdata.service',
             attachTo: { id: 'root', input: 'apis' },
             disabled: false,
           },
@@ -89,7 +89,7 @@ describe('collectLegacyRoutes', () => {
             defaultConfig: {},
           },
           {
-            id: 'api:plugin.stackstorm.service',
+            id: 'api:stackstorm/plugin.stackstorm.service',
             attachTo: { id: 'root', input: 'apis' },
             disabled: false,
           },
@@ -111,7 +111,7 @@ describe('collectLegacyRoutes', () => {
             defaultConfig: {},
           },
           {
-            id: 'api:plugin.puppetdb.service',
+            id: 'api:puppetDb/plugin.puppetdb.service',
             attachTo: { id: 'root', input: 'apis' },
             disabled: false,
           },
@@ -209,7 +209,7 @@ describe('collectLegacyRoutes', () => {
             disabled: false,
           },
           {
-            id: 'api:plugin.catalog.service',
+            id: 'api:catalog/plugin.catalog.service',
             attachTo: {
               id: 'root',
               input: 'apis',
@@ -218,7 +218,7 @@ describe('collectLegacyRoutes', () => {
             disabled: false,
           },
           {
-            id: 'api:catalog-react.starred-entities',
+            id: 'api:catalog/catalog-react.starred-entities',
             attachTo: {
               id: 'root',
               input: 'apis',
@@ -227,7 +227,7 @@ describe('collectLegacyRoutes', () => {
             disabled: false,
           },
           {
-            id: 'api:plugin.catalog.entity-presentation',
+            id: 'api:catalog/plugin.catalog.entity-presentation',
             attachTo: {
               id: 'root',
               input: 'apis',
@@ -241,7 +241,7 @@ describe('collectLegacyRoutes', () => {
         id: 'score-card',
         extensions: [
           {
-            id: 'api:plugin.scoringdata.service',
+            id: 'api:score-card/plugin.scoringdata.service',
             attachTo: { id: 'root', input: 'apis' },
             disabled: false,
           },
diff --git a/packages/core-compat-api/src/collectLegacyRoutes.tsx b/packages/core-compat-api/src/collectLegacyRoutes.tsx
index 197c245278..43e66ce859 100644
--- a/packages/core-compat-api/src/collectLegacyRoutes.tsx
+++ b/packages/core-compat-api/src/collectLegacyRoutes.tsx
@@ -269,7 +269,7 @@ export function collectLegacyRoutes(
         ...extensions,
         ...Array.from(plugin.getApis()).map(factory =>
           ApiBlueprint.make({
-            namespace: factory.api.id,
+            name: factory.api.id,
             params: { factory },
           }),
         ),
diff --git a/packages/core-compat-api/src/convertLegacyApp.test.tsx b/packages/core-compat-api/src/convertLegacyApp.test.tsx
index b76a6c2d71..224ab46221 100644
--- a/packages/core-compat-api/src/convertLegacyApp.test.tsx
+++ b/packages/core-compat-api/src/convertLegacyApp.test.tsx
@@ -65,7 +65,7 @@ describe('convertLegacyApp', () => {
             defaultConfig: {},
           },
           {
-            id: 'api:plugin.scoringdata.service',
+            id: 'api:score-card/plugin.scoringdata.service',
             attachTo: { id: 'root', input: 'apis' },
             disabled: false,
           },
@@ -81,7 +81,7 @@ describe('convertLegacyApp', () => {
             defaultConfig: {},
           },
           {
-            id: 'api:plugin.stackstorm.service',
+            id: 'api:stackstorm/plugin.stackstorm.service',
             attachTo: { id: 'root', input: 'apis' },
             disabled: false,
           },
@@ -103,7 +103,7 @@ describe('convertLegacyApp', () => {
             defaultConfig: {},
           },
           {
-            id: 'api:plugin.puppetdb.service',
+            id: 'api:puppetDb/plugin.puppetdb.service',
             attachTo: { id: 'root', input: 'apis' },
             disabled: false,
           },
diff --git a/packages/core-compat-api/src/convertLegacyApp.ts b/packages/core-compat-api/src/convertLegacyApp.ts
index 2729664941..c3e569e85f 100644
--- a/packages/core-compat-api/src/convertLegacyApp.ts
+++ b/packages/core-compat-api/src/convertLegacyApp.ts
@@ -23,11 +23,12 @@ import React, {
 } from 'react';
 import {
   ExtensionOverrides,
+  FrontendModule,
   FrontendPlugin,
   coreExtensionData,
   createExtension,
   createExtensionInput,
-  createExtensionOverrides,
+  createFrontendModule,
 } from '@backstage/frontend-plugin-api';
 import { getComponentData } from '@backstage/core-plugin-api';
 import { collectLegacyRoutes } from './collectLegacyRoutes';
@@ -61,7 +62,7 @@ function selectChildren(
 /** @public */
 export function convertLegacyApp(
   rootElement: React.JSX.Element,
-): (FrontendPlugin | ExtensionOverrides)[] {
+): (FrontendPlugin | FrontendModule)[] {
   if (getComponentData(rootElement, 'core.type') === 'FlatRoutes') {
     return collectLegacyRoutes(rootElement);
   }
@@ -104,7 +105,6 @@ export function convertLegacyApp(
   const [routesEl] = routesEls;
 
   const CoreLayoutOverride = createExtension({
-    namespace: 'app',
     name: 'layout',
     attachTo: { id: 'app', input: 'root' },
     inputs: {
@@ -127,7 +127,6 @@ export function convertLegacyApp(
     },
   });
   const CoreNavOverride = createExtension({
-    namespace: 'app',
     name: 'nav',
     attachTo: { id: 'app/layout', input: 'nav' },
     output: [],
@@ -139,7 +138,8 @@ export function convertLegacyApp(
 
   return [
     ...collectedRoutes,
-    createExtensionOverrides({
+    createFrontendModule({
+      pluginId: 'app',
       extensions: [CoreLayoutOverride, CoreNavOverride],
     }),
   ];
diff --git a/packages/core-compat-api/src/convertLegacyPlugin.test.tsx b/packages/core-compat-api/src/convertLegacyPlugin.test.tsx
index 3d5b001c61..01266a35b7 100644
--- a/packages/core-compat-api/src/convertLegacyPlugin.test.tsx
+++ b/packages/core-compat-api/src/convertLegacyPlugin.test.tsx
@@ -84,7 +84,7 @@ describe('convertLegacyPlugin', () => {
     });
     expect(internalConverted.featureFlags).toEqual([{ name: 'test-flag' }]);
     expect(internalConverted.extensions.map(e => e.id)).toEqual([
-      'api:plugin.test.client',
+      'api:test/plugin.test.client',
       'page:test',
     ]);
   });
diff --git a/packages/core-compat-api/src/convertLegacyPlugin.ts b/packages/core-compat-api/src/convertLegacyPlugin.ts
index bf5759f214..5fd5e585e6 100644
--- a/packages/core-compat-api/src/convertLegacyPlugin.ts
+++ b/packages/core-compat-api/src/convertLegacyPlugin.ts
@@ -18,7 +18,7 @@ import { BackstagePlugin as LegacyBackstagePlugin } from '@backstage/core-plugin
 import {
   ApiBlueprint,
   ExtensionDefinition,
-  BackstagePlugin as NewBackstagePlugin,
+  FrontendPlugin as NewBackstagePlugin,
   createFrontendPlugin,
 } from '@backstage/frontend-plugin-api';
 import { convertLegacyRouteRefs } from './convertLegacyRouteRef';
@@ -29,7 +29,7 @@ export function convertLegacyPlugin(
   options: { extensions: ExtensionDefinition[] },
 ): NewBackstagePlugin {
   const apiExtensions = Array.from(legacyPlugin.getApis()).map(factory =>
-    ApiBlueprint.make({ namespace: factory.api.id, params: { factory } }),
+    ApiBlueprint.make({ name: factory.api.id, params: { factory } }),
   );
   return createFrontendPlugin({
     id: legacyPlugin.getId(),