Error

When loading the Flex UI, your agents may notice that custom features are missing. A 404 Not Found error appears in the browser developer console when trying to download the bundle.js file for a custom plugin:

404 Not Found for URL: [https://flex.twilio.com/plugins/v1/](https://flex.twilio.com/plugins/v1/)<plugin-name>/<version>/bundle.j

Product

Twilio Flex

Cause

This error occurs when the build asset specified in the active release configuration cannot be served from the CDN or serverless deployment. This typically happens after a plugin update or serverless endpoint redeployment if intermediate caching or build asset references become stale.

Resolution

To resolve this issue, build and release a new version of your Flex plugin:

1. Open your terminal and navigate to your Flex plugin directory.
2. Verify you are using an updated version of the Flex Plugin CLI.
3. Build and deploy a new release version of your plugin package using the CLI.
4. Verify that the new release is set as active in your Flex configuration.
5. Have agents clear their browser cache and refresh the Flex UI.

Additional Information

If the error persists after releasing a new version, capture a HAR log from the affected browser session while reproducing the error to inspect intermediate caching layers and network requests.