HTTP 403 status on the JavaScript Agent or Beacon requests.

toufic_chamandi — Wed, 21 Jan 2026 10:25:08 GMT

Summary: RUM data is sometimes missing because the JS Agent or RUM beacons are being blocked. This article provides information on this issue and how to resolve it.

Problem

You've deployed Dynatrace to your infrastructure and expect to see RUM data, but can't see anything being captured. When you open the developer tools, you notice a 403 status for the JavaScript agent or beacon requests, which hold the RUM data to be sent back to Dynatrace.

JavaScript Agent 403 example:

Beacon requests 403 example:

What is this error and why is this happening?

Definition of 'HTTP 403': HTTP '403 Forbidden' client error response status code indicates that the server understood the request but refused to process it.

This error is usually thrown because you have a firewall that is blocking these requests.

Solution

The fix here is straight forward and there are 2 options you can use:

you will have to unblock these requests. We have a document containing all of the requests and headers that need to be allowed: https://docs.dynatrace.com/docs/shortlink/rum-firewall
Configure a beacon forwarder (This fix does bypass the infrastructure and sends data directly to the cluster ActiveGate but there is a possibility that the traffic is also blocked): Web -> Application -> Settings -> general settings -> Beacon endpoint -> Cluster ActiveGate

What's Next?

If you've completed the troubleshooting steps above but haven't been able to identify the root cause of your issue and solve it, please contact Dynatrace via the in-product chat or by creating a support ticket.

To help our support team investigate efficiently, include the following information:

Access details, if the page is publicly available and you can grant access to the support team.
If access cannot be granted: A HAR file, or, preferably, a Fiddler session capturing the full scenario—ideally with dtHealthCheck enabled.
A brief summary of the troubleshooting steps you've completed.

Providing this information upfront will help speed up the resolution process.

What to read next:

Firewall constraints for RUM

Troubleshooting automatic RUM injection failures

RUM initial setup for web applications

Troubleshooting RUM for web applications

Troubleshooting RUM setup issues for web applications

RUM Application traffic is not captured by Dynatrace.

article HTTP 403 status on the JavaScript Agent or Beacon requests. in Troubleshooting

HTTP 403 status on the JavaScript Agent or Beacon requests.

Problem

What is this error and why is this happening?

Solution

What's Next?