New mystery property $distinct_id_before_identity

  • 13 August 2019
  • 6 replies


We're seeing a new, previously unseen super property called $distinct_id_before_identity on all of our incoming events. Our team has not implemented this property, so we suspect that something has changed on the Mixpanel side. Has anyone else noticed this recently?

6 replies


Hi - this is related to the Identity Management project we're working on here:

When an event comes in with a distinct_id that has been remapped to something else, we are populating this new property with the original value to aid debugging and error resolution. More to come soon, and sorry for the confusion.

[update] This property will no longer show up anywhere in the UI, but is still present on the raw data (as accessed via jql, or other data export endpoints).


Thanks @tim . Is the objective of this project to prevent the pre-login 'orphaned' anonymous events from an existing user? In the meantime, beyond showing up in the UI, this property shows up in the actual event data sent to our webhook destination. I'm just wondering if we need to update all of our events tables to reflect the new property being sent. Is this property eventually going to be a permanent feature exposed to users? Or is it something used by Mixpanel internally to map the anonymous events for a an existing user to their identity?


Yep, assigning pre-login events to the right user is exactly what this project is for!

The property will continue to be populated onto events, but it is definitely for internal use. Up to you if you want to store it or not IMO.


Hey @tim. Could you provide more information on this project, and if there are already changes on the identity management from Mixpanel side? I'm experiencing some weird behavior over the last couple of days, and since we haven't changed the mixpanel integration in our code base recently, we are now suspecting it may be an issue on Mixpanel itself.

What is happening in our case is that the same Mixpanel profile is apparently receiving events from different users. Is this possible (screenshot below), assuming that we didn't call .alias between those two events?



Hi - there are changes but they shouldn't affect you. This is likely due to an alias existing between those two user IDs, which can happen if multiple users log in / sign up on one device and you aren't calling mixpanel.reset() between them.

But can you send more information to please? Need your project ID and link to the profile so we can look into it. Thanks!

Hey @tim  In my case the  distinct id and distinct id before identify are being interchanged after the user comes back to the app and the events are having different distinct ids. 

I don’t understand how this can happen because the before identity distinct id should the random one.