11 Dec 2025 · GTM · low severity · fix verified 9 Sept 2026
Built-in Client ID, Session ID and Session Number variables
'Google Tag Manager now includes three new built-in variables in the Utilities category: Client ID, Session ID, and Session Number.' Plus an Analytics Storage user-defined variable.
What it breaks
Custom cookie-parsing variables that reverse-engineered the _ga cookies are now the fragile path; they break when the cookie format changes.
Who it hits: Anyone passing client or session IDs to a CRM or a data layer.
The fix
Replace cookie-parsing variables with the built-ins.
fix artifact · #A-006
Screenshot-free GTM checklist
Every step named by menu path, never by picture — it survives the interface redesigns that make every screenshot guide wrong.
- verified_on
- 2026-09-09
- next re-check
- 2026-12-01
- status
- current
Sources linked on every entry · artifacts stamped and re-verified · ← all changes