Troubleshooting RUM setup issues for web applications

maliborskaya — Mon, 06 Oct 2025 07:53:49 GMT

The problem

After successfully setting up Real User Monitoring (RUM) for your web application, you should begin to see RUM data appear in your Dynatrace environment. If no data is being captured, this guide will help you identify and resolve potential issues.

💡 Tip: Before diving into the troubleshooting steps, check whether the Application Health Check reports any issues for your application.

Triage

If you're not seeing any RUM data for your application in the Dynatrace web UI, start by verifying that it is receiving traffic. Interact with your application pages to generate user activity.

Once you've confirmed that traffic is flowing to your application, proceed with the steps below.

Check if RUM data is ending up in the wrong application

Check whether the captured RUM data is being assigned to a different application than expected. A common scenario is that the data ends up in the fallback application named My web application.

If this applies to your case, follow the steps outlined in RUM data is assigned to a different application than expected to resolve the issue.

Confirm that the RUM JavaScript has been injected

Load one of your pages, inspect its source in a web browser, and make sure that the <HEAD> element contains a reference to the RUM JavaScript. To identify the RUM JavaScript, proceed as follows.

Automatic injection

Different snippet formats are available for automatic injection. A common characteristic among them is the presence of the string data-dtconfig, either as an attribute or embedded within the code. To verify that the RUM JavaScript has been injected, look for a script element that includes this string.

If you don't see the RUM JavaScript automatically injected by OneAgent into your webpages, refer to Troubleshooting automatic RUM injection failures.

Agentless monitoring

If you're using the snippet format JavaScript tag, search for a script that ends with the string _complete.js and is loaded from js-cdn.dynatrace.com or, in case of Managed, your own CDN. If you use Dynatrace Managed and have not set up your own CDN yet, the script is loaded from a domain in Dynatrace Managed.

If you are using one of the other snippet formats, the string data-dtconfig should be present, either as an attribute or embedded within the code.

If you don't see the RUM JavaScript manually inserted into your webpages, refer to Set up agentless Real User Monitoring.

If you are using the snippet format code snippet and want to check if the second script element containing the full functionality of the monitoring code has been injected successfully, open the Elements tab in the Chrome DevTools and search for an id attribute that contains dtjsagent or dtjsagentdw.

Confirm the successful download of the RUM JavaScript

The Dynatrace RUM JavaScript is downloaded along with the other resources of your web page. To confirm that the download was successful, open the Network tab in your browser’s developer tools. Look for a request URL that contains one of the following strings:

_complete.js if you're using the JavaScript tag snippet format
ruxitagent – for other snippet formats, or
your custom monitoring code filename prefix, if you've configured one.

The response should have a 200 OK status and the body should contain JavaScript code.

An example is shown in the screenshots below.

If the RUM JavaScript hasn't downloaded correctly, refer to RUM JavaScript isn't downloadable.

Confirm the successful initialization of the RUM JavaScript

To check if the RUM JavaScript has initialized successfully on your page, check whether the dT_ JavaScript object exists. Open your browser developer console, enter dT_, and press Enter. As a result, an object should be returned. Otherwise, you will find logs in the browser console that help you identify the issue.

Confirm that RUM data is being sent to Dynatrace

The RUM JavaScript sends the captured data as beacon requests—which are HTTP POST requests—to a designated beacon endpoint.

For automatic injection, the beacon endpoint is, by default, provided by the OneAgent that instruments your application.
For agentless monitoring, the beacon endpoint is, by default, provided by a Cluster ActiveGate.

Alternative configurations are possible, see Configure beacon endpoint for web applications.

You can check these requests in the Network tab of your browser's developer tools.

If the beacon requests are handled by OneAgent, look for requests with a URL where the path begins with rb_.

If a Cluster ActiveGate is used, you can identify beacon requests as follows:

If you are using Dynatrace SaaS, beacon requests go to Dynatrace, and their URL path begins with bf.
If you are using Dynatrace Managed, the requests are directed to a domain in Dynatrace Managed, and their URL path begins with bf.

Responses should have the 200 OK status, and the response body should start with OK. If the response body starts with FL, the RUM beacon was rejected and not forwarded to the server. The response contains additional information about the problem. For further details, check RUM JavaScript doesn't report data to server.

Common issues

This section provides guidance on how to further troubleshoot the issues identified during the triage process above.

RUM JavaScript isn't downloadable

If you see that the RUM JavaScript isn't downloadable, there might be a few reasons for that.

For agentless monitoring

The RUM JavaScript is incorrect. Refer to Set up agentless Real User Monitoring to verify your setup.
Content Security Policy rules prevent loading of the RUM JavaScript. Adapt your CSP rules as described in Modify Content Security Policy for RUM.
The RUM JavaScript host https://js-cdn.dynatrace.com isn't reachable for client browsers due to firewall rules or proxy server configuration. Connections to and from the host must be allowed.

For automatic injection on web servers

Rules on firewalls, load balancers, or proxies aren't configured to allow RUM JavaScript download. Refer to Firewall constraints for RUM for details.

For automatic injection on Java application servers

Root application doesn't exist. The RUM JavaScript is usually loaded from the web server root path (.../ruxitagentjs_...).
Your Java application server serves static content in a way that doesn't use the servlet stack. In such cases, the RUM JavaScript can't be downloaded.

To resolve a JavaScript download issue caused by a missing root application, configure an accessible path (for example, a valid servlet path) as described in Modify the monitoring code URL path.

RUM JavaScript doesn't report data to server

If you see that the RUM beacons are rejected and not forwarded to the server, there might be several reasons for that.

Rules on firewalls, load balancers, or proxies may need to be adapted. Refer to Firewall constraints for RUM for details.
Beacons may fail if their auto-selected URL path is blocked, but you can fix this by adjusting the URL before the rb_ prefix. Read more here.
Dynatrace throttled the capture rate of your application.
Content Security Policy settings may need to be adapted as described in Modify Content Security Policy for RUM.

What's Next?

If you're still not seeing any RUM data for your application after completing the troubleshooting steps above, please reach out to Dynatrace via the in-product chat or by creating a support ticket for further assistance. Provide the following information:

Link to the RUM application in Dynatrace,
Link to the related Service(s) or Process Group(s) in Dynatrace,
State the issue and the troubleshooting that you have completed,
Link to the application being monitored with steps to reproduce the issue.
- If the application is not publicly available, provide a HAR file.

Re: Web applications: Issues with RUM JavaScript

Kenny_Gillette — Wed, 20 Mar 2024 17:42:36 GMT

Wow, great doc! Definitely saving this.

Re: Web applications: Issues with RUM JavaScript

Taylor-Sanchez — Thu, 21 Mar 2024 03:00:00 GMT

This is a wonderful reference! Thanks for taking the time to write something like this up - I'm sure a lot of people will find it useful when troubleshooting!

Re: Web applications: Issues with RUM JavaScript

GerardJ — Thu, 21 Mar 2024 08:49:26 GMT

Really great work! Many thanks to you

Re: Web applications: Issues with RUM JavaScript

AlvinPeterson — Wed, 17 Apr 2024 11:57:40 GMT

Great stuff here! Thank you!

Re: Web applications: Issues with RUM JavaScript

sujit_k_singh — Mon, 29 Apr 2024 18:19:45 GMT

Very helpful.

Re: Web applications: Issues with RUM JavaScript

Amarnadh_Sunkar — Fri, 21 Feb 2025 17:48:05 GMT

Hi ,

Dynatrace Java script is not injecting for me , we have akamai and another webser , what is the trouble shooting that i can do.

Re: Web applications: Issues with RUM JavaScript

erh_inetum — Mon, 24 Feb 2025 07:10:19 GMT

Hi @Amarnadh_Sunkar ,

We had the same situation and we solved it configurating the application as agentless. Here you have the documentation.

Hope it helps.

Regards,

Elena.

Re: Web applications: Issues with RUM JavaScript

Amarnadh_Sunkar — Mon, 03 Mar 2025 04:41:42 GMT

Thanks Elena,

I am trying in agentless , do you have any time to connect for 30 minutes.

Re: Web applications: Issues with RUM JavaScript

lekpamartin — Thu, 15 May 2025 07:23:58 GMT

Very helpful

Re: Web applications: Issues with RUM JavaScript

Doaa_Sobhy — Wed, 16 Jul 2025 10:55:59 GMT

Thank you for that great efforts

article Troubleshooting RUM setup issues for web applications in Troubleshooting

Troubleshooting RUM setup issues for web applications

The problem

Triage

Check if RUM data is ending up in the wrong application

Confirm that the RUM JavaScript has been injected

Automatic injection

Agentless monitoring

Confirm the successful download of the RUM JavaScript

Confirm the successful initialization of the RUM JavaScript

Confirm that RUM data is being sent to Dynatrace

Common issues

RUM JavaScript isn't downloadable

For agentless monitoring

For automatic injection on web servers

For automatic injection on Java application servers

RUM JavaScript doesn't report data to server

What's Next?

Re: Web applications: Issues with RUM JavaScript

Re: Web applications: Issues with RUM JavaScript

Re: Web applications: Issues with RUM JavaScript

Re: Web applications: Issues with RUM JavaScript

Re: Web applications: Issues with RUM JavaScript

Re: Web applications: Issues with RUM JavaScript

Re: Web applications: Issues with RUM JavaScript

Re: Web applications: Issues with RUM JavaScript

Re: Web applications: Issues with RUM JavaScript

Re: Web applications: Issues with RUM JavaScript