dev.botframework.com shows blank white screen; all.js 404 / DevPortal is not defined

Question

dev.botframework.com shows blank white screen; all.js 404 / DevPortal is not defined

Bowen He 0

Summary

I cannot load the Bot Framework portal at https://dev.botframework.com/bots on my devices. The page stays a blank white screen. A colleague can open the same site on their computer and successfully update my bot’s messaging endpoint for me.

Environment / what I tried

URL: https://dev.botframework.com/bots
Devices: my computer and my iPhone — both fail
Networks tried: Wi‑Fi, mobile 5G, and VPN — all still white screen
Colleague’s computer on their network: site loads normally and they can manage the bot

Symptoms

Page shell may load, but UI never becomes usable (blank white screen)
Same failure across browsers/devices on my side

Browser DevTools console (relevant errors)

Failed to load resource: the server responded with a status of 404 () Resource: https://dev.botframework.com/Client/Generated/v4/all.js
Refused to execute script from 'https://dev.botframework.com/Client/Generated/v4/all.js' because its MIME type ('') is not executable, and strict MIME type checking is enabled.
jQuery.Deferred exception: DevPortal is not defined ReferenceError: DevPortal is not defined (also: Uncaught ReferenceError: DevPortal is not defined)
Uncaught (in promise) Error: A listener indicated an asynchronous response by returning true, but the message channel closed before a response was received (may be extension-related)

There were also “Slow network is detected” interventions for fonts from a Chrome extension, but the blocking issue appears to be the failed all.js load.

Notes

Azure Portal itself works for me for some Entra / App registration views, but I do not have access to an Azure Bot resource / subscription view on my account (separate AccessDenied when listing some resources). The Bot Framework portal white-screen issue is specifically what I’m asking about here.
Workaround in use: colleague updates the messaging endpoint on my behalf from their working session.

Questions

Why would Client/Generated/v4/all.js return 404 (and empty MIME type) for my client while another user can load the portal successfully?
Is this a known CDN / regional / account / WAF routing issue for Bot Framework Developer Portal?
What should I collect next (HAR, edge location, tenant/account type) to help diagnose?
Is there an official alternative to https://dev.botframework.com/bots for updating a bot messaging endpoint when this portal fails?

I can attach full DevTools screenshots / HAR if needed. Please do not ask for client secrets or bot passwords.

0 comments

1 answer

Your answer

Answer 1

Hi Bowen,

The all.js request returning 404 is the immediate cause of the blank page. DevPortal is not defined is a consequence of that script not loading.

For an Azure-managed bot, you do not need dev.botframework.com to change the messaging endpoint. Microsoft documents the Azure Portal as the supported configuration path:

Azure Portal → Azure Bot resource → Settings → Configuration → Messaging endpoint → Apply.

You can also update it directly with Azure CLI:

az bot update \
  --resource-group <resource-group> \
  --name <bot-name> \
  --endpoint https://<your-host>/api/messages

Microsoft documents this command specifically for updating the Azure Bot messaging endpoint.

Given that dev.botframework.com/Client/Generated/v4/all.js itself returns 404, changing DNS, extensions, or browser settings is unlikely to fix that particular failure. Use the Azure Bot resource configuration instead.