Call a Screen Flow from Apex

Question

I've created a visualforce page with an Apex controller and have a button that should open a Screen Flow but am unable to do so.

Here is the code that should call the flow:

public void openOpportunityFlow() {
        Map<String, Object> inputVariables = new Map<String, Object>();
        inputVariables.put('LeadId', selectedLeadId);

        String flowApiName = 'Open_Opp_Screen_Flow';

        Flow.Interview flowInterview = Flow.Interview.createInterview(flowApiName, inputVariables);

        flowInterview.start();
}

The error I'm getting is "Start can't be called on a flow with the process type Screen Flow."

I've done some searching online and am having trouble finding anyone else with the issue.

Answer 1

You cannot run a screen flow from Apex. You need to use a UI mechanism to launch them, such as lightning-flow for LWC.

In Apex there's no UI context - Apex is entirely backend - so the flow cannot execute (it has nowhere to show the screens). You can invoke auto-launched flows from Apex.

Answer 2

Unfortunately, you cannot "start" a screen flow as mentioned in this Apex Reference Guide

This method (start) can be used only with flows that have one of these types.

 - Autolaunched Flow
 - User Provisioning Flow