RUM feature "Use Proxy API for XHRs" breaks application functionality.

[KiranSomanatti]

• Summary
• Problem
• Troubleshooting steps
• Resolution
• What's next

 

Summary

Some Real User Monitoring (RUM) - instrumented applications may show empty page sections because XHR requests are never triggered, preventing required content from loading.

This behavior may occur when the “Use Proxy API for XHRs” feature in related RUM application is enabled.

 

Problem

The new Proxy API–based XHR wrapper introduced with the “Use Proxy API for XHRs” feature can break in environments where:

• The application overrides the global Map object, and
• The implementation is not specification‑compliant.

This causes the Proxy XHR wrapper to fail silently, blocking XHR execution.

 

Troubleshooting steps

• Disable the “Use Proxy API for XHRs” feature.
• Verify whether the application overrides the global Map object by running  dT_.gdi() command in browser console.
• Check for warnings related to Map.

If that is true, and application has non spec compliant implementation of the Map object, the Proxy XHR wrapper will not work.

 

Resolution

 

Option 1 (Recommended long‑term fix)

Ensure the monitored application's global Map implementation is compliant with Map object specification. A compliant Map allows the Proxy XHR wrapper to function correctly.

 

Option 2 (Immediate workaround)

Disable the “Use Proxy API for XHRs” feature and rely on the Basic XHR module (Capture XmlHttpRequest (XHR) option).

• No loss of XHR capture
• Page content renders normally
• Only the wrapping mechanism changes

 

What's next

If this article did not help, please open a support ticket, mention that this article was used and provide the following in the ticket:

• link to related RUM Application
• information if the monitored application's global Map implementation is compliant with Map object specification.

[KiranSomanatti]

Also there are linked error same to as this:

Possible error in colsole be like :

Uncaught TypeError: xyz has is not a function

This happens if the customer's page contains a Map polyfill that does not comply with the standard

How to check:

• type “new Map().has” into the console of the developer tools in browser. If it does not show something like ƒ has() { [native code] }, but undefined, then this is the case.

  

• If it is the case, type Map into the developer tools and press enter. This will provide some more information about the implementation of Map and where the polyfill is coming from.

• This issue needs to be fixed by the customer. Map is a standard library in all supported browsers!