Launch Flow from Button in Lightning Community - "down for maintenance" error

Question

Summary: I'm getting a "down for maintenance" error in my Lightning community when I click a custom button that launches a screen flow to create a user from an existing contact. The button works in Salesforce, but not the Lightning community.

Expected:

1. User opens a Contact record.
2. User clicks the "Create User" button.
3. The button launches a screen flow to create the user and passes in the Contact.Id.
4. The flow processes. If successful, the user clicks "Finish" and is redirected back to the Contact's record.

Actual:

1. User opens a Contact record.
2. User clicks the "Create User" button.
3. A new tab opens with the force.com down for maintenance message:

Community-url is down for maintenance. Sorry for the inconvenience. We'll be back shortly. Please email us if you need to get in touch.

URL of the error page: community-url/flow/Create_Community_User?contact_id=0031h00000Ms2QE&retURL=community-url/0031h00000Ms2QE

Button Config:

/flow/Create_Community_User?contact_id={!Contact.Id}&retURL=community-url/{!Contact.Id}

Even if I simplify the button to just be /flow/Create_Community_User?contact_id={!Contact.Id}, I get the same error.

Also, I tried using the "Flow" component in the community instead, and that works when I pass in the correct IDs (so the flow itself seems to be working). I don't want to use the component because I still need a button or something to trigger this - I don't want the flow to trigger any time someone lands on a Contact's page.

Any ideas on why this is happening?

Answer 1

I FIGURED IT OUT

I couldn't use that button in lightning because it was passing in field parameters. Instead, I created a custom action on Contact that launched my flow. I made sure my Contact.Id variable was named "recordId," because SF requires this in order to pass in the ID while launching the flow (documentation). Works perfectly now.