How can I restore/reuse a deleted RUM session property key?

[Mohsen]

Hi,

I previously added a Session and User Action Property with the key env to our Dynatrace RUM web application and later deleted it.

Now I need to add env back, but Dynatrace gives me this error: Tag with key env was deleted before

Is there a way to restore a deleted property or allow the same key (env) to be created again?

[Julius_Loman]

I remember that you need to wait for at least 35 days so that the property will expire with the historical data.

[t_pawlak]

Yes, that matches my understanding as well.

Once a RUM session/user action property key is deleted, Dynatrace keeps it reserved while historical data referring to that property still exists. Therefore, the same key can't be recreated immediately.
Waiting for the historical data retention period to expire should make the key reusable again

If you need the property immediately, the practical workaround would be to use a different key, for example environment or app.env
If waiting isn't an option, it may also be worth opening a Dynatrace support ticket to confirm whether the deleted key can be cleared manually for your environment.