Summary
Dynatrace Synthetic Browser Monitors can be automatically assigned to Real User Monitoring (RUM) applications when they execute against pages that include RUM JavaScript injection. This automatic assignment enables deeper analysis by linking synthetic executions with user sessions, actions, and distributed traces inside the application view.
In some scenarios, however, automatic assignment doesn’t occur as expected. This article explains how application auto‑assignment works, why it may fail, and what to verify when a Browser Monitor isn’t linked to a RUM application.
- Summary
- What is Application auto-assignment?
- Why this matters
- How linking works between Browser Monitors and RUM
- Examples
- Troubleshooting missing automatic assignment
- 1. Confirm the Browser Monitor visits a RUM‑injected page
- 2. Check the position of the RUM JavaScript (jsAgent) tag
- 3. Verify that Synthetic executions are not excluded from RUM injection
- 4. Verify that the RUM JavaScript (jsAgent) tag matches the expected format
- 5. Verify that the RUM JavaScript (jsAgent) is a supported version
- Key limitations to be aware of
- What's Next
- Related reading
What is Application auto-assignment?
Application auto‑assignment occurs when a Browser Monitor visits a page that has Dynatrace RUM injection enabled. During execution, the Dynatrace Synthetic Player detects the RUM JavaScript and automatically associates the Browser Monitor with the corresponding RUM application.
Why this matters
Automatic assignment provides several benefits compared to manual assignment:
- Synthetic sessions appear inside the RUM application as sessions from a Synthetic user
- You can analyze Browser Monitor executions using Session Segmentation
- You can navigate between user actions and synthetic executions
- Related distributed traces can be accessed directly from Browser Monitor results
This correlation helps connect availability issues detected by Synthetic Monitoring with real application behavior and backend performance.
How linking works between Browser Monitors and RUM
When auto‑assignment is successful, Dynatrace creates bidirectional links:
- From a RUM user action, you can jump to the corresponding Browser Monitor execution
- From a Browser Monitor execution, you can open the related user action in the RUM application
- From a Browser Monitor execution, you can access traces via the Detailed breakdown section
These links make it easier to troubleshoot performance or availability issues end‑to‑end.
Examples
Session Segmentation
Link from a user action in a user session to a Browser Monitor execution
Clicking on Perform Waterfall Analysis for an action in a Session will take you to the step in the relevant execution in Synthetic Monitoring
Link from a Browser Monitor execution to a user action
The link also works in reverse. Browser Monitor executions link to the relevant User Action in the RUM Application. Clicking on the user action link, a clickable URL in blue, will open the relevant User Action details page.
Link to traces from a Browser Monitor
To view traces from a Browser Monitor, open an execution and click on the relevant event. Scroll down to the 'Detailed breakdown' section and click on the Traces tile, as shown here
Troubleshooting missing automatic assignment
If a Browser Monitor is not automatically assigned to a RUM application, verify the following.
1. Confirm the Browser Monitor visits a RUM‑injected page
Automatic assignment only works if the pages visited by the Browser Monitor are actually injected with RUM. If the monitor never reaches an injected page, no application information can be detected
2. Check the position of the RUM JavaScript (jsAgent) tag
For Synthetic Monitoring, the RUM JavaScript must be the first script loaded on the page.
- This requirement is specific to Synthetic executions
- Real users may still be monitored even if the script isn’t first
If automatic injection is used, you can configure an injection rule to control where the script is inserted. If manual injection is used, work with the team managing the page to ensure the
jsAgent script tag is loaded first.3. Verify that Synthetic executions are not excluded from RUM injection
When manual injection is used, confirm that there are no rules excluding Synthetic executions from RUM injection. If Synthetic traffic is excluded, the Browser Monitor cannot be auto‑assigned to an application.
4. Verify that the RUM JavaScript (jsAgent) tag matches the expected format
If manual injection is being used, confirm that the jsAgent script filename matches expected format:
<name>_<featurehash>_<version>.js or <appid>_complete.jsSynthetic only supports these formats.
5. Verify that the RUM JavaScript (jsAgent) is a supported version
Confirm that the jsAgent is a supported version, using the Application Health check.
Key limitations to be aware of
- Automatic assignment cannot be disabled if a Browser Monitor visits a RUM‑injected page
- Assignment is detected at runtime, not during monitor configuration
- Manual assignment is still possible, but auto‑assignment provides deeper correlation
Understanding these constraints helps set expectations when designing Synthetic Monitoring strategies.
What's Next
If you've resolved the issues highlighted above but are still not seeing any Synthetic sessions in your RUM Application, then please open a chat or Support ticket and provide the following information:
- Link to the Browser Monitor in your environment
- Link to the RUM Application in your environment
Related reading
📖 Synthetic Troubleshooting Map
