Rizla

[left dome]

👋 Thanks for reaching out

Can you share the ID (req_xxx) of the failing API request?
https://support.stripe.com/questions/finding-the-id-for-an-api-request

When updating a subscription only now or unchanged can be passed to billing_cycle_anchor:
https://stripe.com/docs/api/subscriptions/update#update_subscription-billing_cycle_anchor