I’m trying to cancel existing subscriptions.
I think I need to use " Update a subscription" but I can’t find out what kind of values I exactly need to add. Do I need to create a session for that in order to work?
Hi @norman,
Thank you for reaching out.
Update a subscription action is used to update an existing subscription to match the specified parameters. This action call has multiple uses depending on what fields you fill in.
Update a subscription action call gives you the option to:
Change the plan /* If you want to replace the current plan of a customer with another you will have to fill in these fields: Subscription ID, Subscription item ID, and the Plan ID of the new plan you want to subscribe a customer to.*/
Add additional plans /* A customer can be subscribed to multiple plans. To add an additional plan to a customer you will need to fill in these fields: Subscription ID, and the Plan ID. This will create another Subscription item ID so make sure you store it somewhere for later use.*/
Change the billing source /* If you want to change the default billing source for a customer’s subscription you will need to fill in the Card ID field with an existing card ID from that customer.
Cancel the subscription /* To cancel an existing subscription at the end of the current billing period just fill in the Subscription ID and Cancel at the period end fields.*/
Below you can find a setup example from the Paystart - Stripe Payments Kit template. Also, you can check the template live demo page.
I hope that the above will be helpful for you. 
Have a great weekend ahead.
Regards,
@Igor sorry to bother again. I set up all the fields. But Stripe is giving me this error log:
I think I didn’t refresh the Log window properly. When I entered the sub_id and tried again it worked. But now is the question how can I save the sub_id of the subscription during my Create a session process?
@Igor can you please tell me why I can’t get the sub_id when I subscribe with “Create a session” ? It should be selectable as Result of step X (Create a Session) but only Session ID, Error and Intend ID is selectable.
Hi @norman,
Thank you for your message and sorry for the late reply due to the weekend.
In order to retrieve the Subscription ID, you have to use the action Create a Subscription first, and after that retrieve its ID as the Result of step X. For references, see the screenshot below:
Please try my suggestions and let me know if they worked.
Take care,
Yes that worked. Thanks 
