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visitor id not changing after deleting cookies (mobile website)


Level 1

Hi all,


Lately, I am encountering some weird behaviours of the visitor id value. 

So, what happens is this:

- I open my website on chrome from an Android phone

- I accept the cookies and I am assigned a visitor ID (ex "123456").

- I delete all the cookies (especially the demdex ones).

- I close the browser, I open it again and I accept the cookies again.

- I am assigned exactly the same visitor ID ("123456") that was aassigned before to me.

How is it possible? If I do the same procedure navigating from the web (not mobile), the visitor ID assigned is always different (as it should be).
Any insight on how and why this is happening? 

Thank you very much in advance for any help you'll give me.



5 Replies


Community Advisor

Adobe might be reassigning the value based on your Device ID?? I know Adobe tries to do its best to re-identify users; so that our UV stats aren't impacted by - or less impacted - by things like ITP....


This is the first time I've actually heard someone consider features to improve UV counts an issue  


What about using an Incognito or Private tab on your mobile browser? Does that work?


Level 1

Hi Jennifer,

It is a good insight the device ID, I will surely look into it better, thanks, even though this behaviour seems to happen only on certain browser like Chrome, Edge, and Canary.

If I use Opera that does not happen, and firefox and Safari I could not test them yet, but I am pretty sure that because of their ITP I am going to be assigned a different visitor id each time I delete cookies.

As for your question, if I use an incognito tab on mobile, I am assigned a new visitor ID every time I close and open the tab again, which is what I expect.


Apart from the device ID, I was also thinking that maybe the IP address could be used by Adobe to identify ''returnirng'' users, but even by using a VPN service, the results do not change. 
I am just trying to understand if what is happening is a behaviour that depends on Adobe, or if I have to look for the issue in my code.



Level 1

Hi Jennifer,


it's me again  can you provide some more info on the device ID you have mentioned above? I tried to look into Adobe's documentation but I could not find much info, probably I am not looking for the right thing.

Thanks again for the help!


Community Advisor

A lot of Adobe's fingerprinting techniques aren't always documented... I know that they use a combination of techniques...


For the Device ID, I know this tends to be more of a Mobile App thing, but it's possible that some browsers are sending this through. or that Adobe has started listening for it in certain scenarios...


It seems like this should be reset with cookies, unless not all cookies are being cleared?



The other possibility could be that you have a shared resource from another site in your network, that Adobe might be seeing the ECID from that other server? But unless you have an adaptive site that might change what resources are included based on certain criteria, I would expect this to act consistently across browsers / devices.....



Level 5

Hi Sofia,

What you're encountering seems unusual because typically, when you delete cookies (including the demdex cookie), you should be assigned a new visitor ID when you visit the site again, since the Adobe Experience Cloud ID Service uses the demdex cookie to store the visitor ID.