Migration to v4 : No provider for: @jupyterlab/apputils:IThemeManager

Hello everyone,

I am trying to migrate a theme to jupyterlite 0.2.0 (hence jupyterlab v4) and after trying a lot of different things, I can’t seem to make it work. The build is successful but my theme fails to activate and I get the following error:

index.es6.js:2015 TypeError: No provider for: @jupyterlab/apputils:IThemeManager.

Here is my package.json:

  "name": "@custom/theme-light",
  "version": "0.1.0",
  "description": "A custom Light theme for JupyterLab",
  "keywords": [
  "files": [
  "main": "lib/index.js",
  "types": "lib/index.d.ts"
  "scripts": {
    "build": "jlpm build:lib && jlpm build:labextension:dev",
    "build:prod": "jlpm build:lib && jlpm build:labextension",
    "build:labextension": "jupyter labextension build .",
    "build:labextension:dev": "jupyter labextension build --development True .",
    "build:lib": "tsc",
    "dist": "cd ../../dist && npm pack ../packages/custom",
    "clean": "jlpm clean:lib",
    "clean:lib": "rimraf lib tsconfig.tsbuildinfo",
    "clean:labextension": "rimraf ../../custom/labextension",
    "clean:all": "jlpm clean:lib && jlpm clean:labextension",
    "docs": "typedoc src",
    "watch": "run-p watch:src watch:labextension",
    "watch:src": "tsc -w",
    "watch:labextension": "jupyter labextension watch ."
  "dependencies": {
    "@jupyterlab/application": "^4.0.7",
    "@jupyterlab/apputils": "~4.1.7"
  "devDependencies": {
    "@jupyterlab/builder": "^4.0.0",
    "npm-run-all": "^4.1.5",
    "rimraf": "^5.0.1",
    "typescript": "~5.2.2",
    "yarn-deduplicate": "^6.0.2"
  "sideEffects": [
  "jupyterlab": {
    "extension": true,
    "themePath": "style/index.css",
    "outputDir": "../../custom/theme-light"
  "jupyterlite": {
    "liteExtension": true

And the retty standard index.js:

import {
} from '@jupyterlab/application';

import { IThemeManager } from '@jupyterlab/apputils';

const extension: JupyterFrontEndPlugin<void> = {
  id: '@custom/theme-light',
  requires: [IThemeManager],
  autoStart: true,
  activate: (
    app: JupyterFrontEnd, 
    manager: IThemeManager ) => {
    const style = '@custom/theme-light/index.css';

      console.log("activate theme?")

      console.log("manager %o", manager);

        name: 'Custom Light',
        isLight: true,
        themeScrollbars: true,
        load: () => manager.loadCSS(style),
        unload: () => Promise.resolve(undefined)

export default extension;

Of course I checked the changelog but haven’t find anything on IThemeManager changing from v3. I tried to switch the IThemeManager to “optional” but without success.

Thank you in advance for any guidance you may provide!


It is hard to say if this is an issue in JupyterLite or JupyterLab. Do you also see it in plain JupyterLab? Can you open an issue in respective repository?

1 Like

Hi @krassowski, thank you for your response.

I had give up on the migration for now. I tried again and encountered similar issues. In most cases, the “TypeError: No provider for: X” errors were due to conflicting versions. Check the package.json of your different extensions. Remove node_modules and install again.