Inaccurate domain_sessionid values

Hi everyone

We’ve implemented Snowplow JS tracker (v. 2.18.2) via Google Tag Manager and we suspect that it doesn’t deduplicate domain_sessionid properly.

The single tracker (and so the collector url) is used across multiple websites.

Instead of generating a single domain_sessionid in the activity session, we’re seeing multiple domain_sessionid, sometimes even for each page viewed within the session.

Mostly iOS users are impacted by this.

What could be the reason for this? Is it possible that we’re blocked by some browser with writing into the local storage? Especially if the collector URL is from a different context than the client website?

Hi @mac-dtm

This is probably due to not specifying the cookieSameSite to be at least ‘Lax’, iOS doesn’t play nice with ‘none’.

 appId: 'website_X', 
    discoverRootDomain: true, 
    stateStorageStrategy: 'cookieAndLocalStorage',
    cookieSameSite: 'Lax',

Thank you for this answer! Let me check and circle back with some update for the community.