New RUM - Custom event and session properties

reshef — Mon, 27 Apr 2026 11:34:16 GMT

Hi,
We have just moved to the new RUM experience, and much to my surprise the new frontend settings for Event and session properties does not seem to include the option to add custom properties - unless via the JS RUM API. Is that really the case?

We're relying heavily on session and user action properties in our frontend monitoring, mostly with CSS selectors, and we don't always have the option to modify the code in these applications (for example with out of the box services like SAP and Tableau).

Re: New RUM - Custom event and session properties

t_pawlak — Mon, 02 Feb 2026 16:20:38 GMT

Hi,

In the New RUM Experience, Event and session properties for web frontends:

must be configured/defined first, otherwise incoming properties are dropped during ingest,
and the documented way to provide values is via the JS RUM API (addEventModifier for event properties, sendSessionPropertyEvent for session properties).
there are explicit limits (for example max 20 configured properties, naming/value limits).

Everything you can find here: https://docs.dynatrace.com/docs/observe/digital-experience/new-rum-experience/web-frontends/additional-configuration/event-and-session-properties

Given you rely heavily on CSS-selector-based action/session properties and often can’t modify application code (for example SAP and Tableau), the important nuance is:

New RUM currently runs alongside RUM Classic, and you can’t fully migrate away from Classic yet.
Event & session properties are explicitly separate from RUM Classic “user action & session properties” (the Classic ones are where CSS selector capture lives).

Here documentation where everything is explain: https://docs.dynatrace.com/docs/observe/digital-experience/new-rum-experience/relationship-to-rum-classic

So in practice:

DOM/CSS selector / meta-tag style capture → keep using RUM Classic user action & session properties.
New RUM event & session properties → effectively require JS API; without a way to inject or run custom JS, they won’t replace your selector-based setup 1:1.

topic New RUM - Custom event and session properties in Real User Monitoring

New RUM - Custom event and session properties

Re: New RUM - Custom event and session properties