loadClerkJsScript broken clerk/react

Preliminary Checks

• I have reviewed the documentation: https://clerk.com/docs

• I have searched for existing issues: https://github.com/clerk/javascript/issues

• I have not already reached out to Clerk support via email or Discord (if you have, no need to open an issue here)

• This issue is not a question, general help request, or anything other than a bug report directly related to Clerk. Please ask questions in our Discord community: https://clerk.com/discord.

Reproduction

https://github.com/iloveitaly/python-starter-template/blob/7f5b650dd9c305d1aa12058bfde456d4390689d2/web/app/configuration/clerk.tsx

Publishable key

pk_test_bWVycnktamF3ZmlzaC00LmNsZXJrLmFjY291bnRzLmRldiQ

Description

This situation:

• Latest React Router SPA
• clientLoader that wants to use clerk authentication to hit a API endpoint
• React page which uses clerk UI components

Causes Clerk was not loaded with Ui components to be thrown.

This occurs because:

1. clientLoader calls getClient()
2. getClient loads clerk JS if window.Clerk is not available
3. something changed recently where loadClerkJsScript, clerk.load(), or the JS that is dynamically loaded causes the UI stuff to not get loaded.

Here's the getClient implementation:

export async function getClient() {
  const windowWithClerk = window as Window & { Clerk?: LoadedClerk }

  if (!windowWithClerk.Clerk) {
    // recommended officially here:
    // https://clerk.com/docs/references/sdk/frontend-only#call-window-clerk-load
    await loadClerkJsScript({
      publishableKey: CLERK_PUBLIC_KEY,
    })
  }

  invariant(windowWithClerk.Clerk, "Clerk should be defined")

  const clerk = windowWithClerk.Clerk

  if (!clerk.loaded) {
    await clerk.load()
  }

  // protect users from hitting the internal API if they aren't authenticated
  if (!clerk.user) {
    await clerk.redirectToSignIn()
    return
  }

  return clerk
}

I think a recent change in the dynamically loaded clerk javascript has caused UI components to not be loaded when you load the clerk javascript outside of the React provider. I believe the culprit is the dynamically loaded clerk code because dropping package versions did not fix the issue and I've have tests from ~2w ago where this worked just fine.

Attempted discord but got no useful response.

Steps to reproduce:

https://github.com/iloveitaly/python-starter-template/blob/7f5b650dd9c305d1aa12058bfde456d4390689d2/web/app/configuration/clerk.tsx

this file and the surrounding repository replicates the failure.

Expected behavior:

UI components loaded & the ability for me to access a clerk client (a) without calling the clerk endpoints twice and using clerk-js (b) before the react render cycle has run (i.e. within clientLoader).

Actual behavior:

The following exception is thrown when a page is loaded that contains Clerk React UI components.

Error: Clerk was not loaded with Ui components
    at nG.assertComponentsReady (https://notable-rhino-51.clerk.accounts.dev/npm/@clerk/clerk-js@6/dist/clerk.browser.js:18:214256)
    at nG.mountUserButton (https://notable-rhino-51.clerk.accounts.dev/npm/@clerk/clerk-js@6/dist/clerk.browser.js:18:180854)
    at Object.mountUserButton [as mount] (https://python-starter-template.localhost/node_modules/.vite/deps/@clerk_react.js?v=a49ee953:6045:50)
    at ClerkHostRenderer.componentDidMount (https://python-starter-template.localhost/node_modules/.vite/deps/@clerk_react.js?v=a49ee953:3897:45)
    at Object.react_stack_bottom_frame (https://python-starter-template.localhost/node_modules/.vite/deps/client-CS_gmzuS.js?v=a49ee953:12882:14)
    at runWithFiberInDEV (https://python-starter-template.localhost/node_modules/.vite/deps/client-CS_gmzuS.js?v=a49ee953:851:66)
    at reappearLayoutEffects (https://python-starter-template.localhost/node_modules/.vite/deps/client-CS_gmzuS.js?v=a49ee953:7532:57)
    at recursivelyTraverseReappearLayoutEffects (https://python-starter-template.localhost/node_modules/.vite/deps/client-CS_gmzuS.js?v=a49ee953:7588:65)
    at reappearLayoutEffects (https://python-starter-template.localhost/node_modules/.vite/deps/client-CS_gmzuS.js?v=a49ee953:7578:14)
    at recursivelyTraverseReappearLayoutEffects (https://python-starter-template.localhost/node_modules/.vite/deps/client-CS_gmzuS.js?v=a49ee953:7588:65)

Environment

System:
    OS: macOS 26.4.1
    CPU: (12) arm64 Apple M2 Max
    Memory: 186.81 MB / 96.00 GB
    Shell: 5.9 - /opt/homebrew/bin/zsh
  Binaries:
    Node: 24.15.0 - /Users/mike/.local/share/mise/installs/node/24.15.0/bin/node
    npm: 11.12.1 - /Users/mike/.local/share/mise/installs/node/24.15.0/bin/npm
    pnpm: 11.1.2 - /Users/mike/.local/share/mise/installs/pnpm/11.1.2/pnpm
    bun: 1.3.14 - /Users/mike/.local/share/mise/installs/bun/1.3.14/bin/bun
    Deno: 2.7.11 - /opt/homebrew/bin/deno
  Browsers:
    Chrome: 148.0.7778.168
    Chrome Canary: 150.0.7835.0
    Firefox: 139.0.1
    Safari: 26.4
    Safari Technology Preview: 26.0