SOLVED – Can’t perform callout when resuming a flow or inside an Apex Queueable

If you have a Scheduled Salesforce Flow that includes an HTTP Callout element and you are getting this error:

Callout failed for invocable action {Action}. Can’t perform callout when resuming a flow or inside an Apex Queueable. Place the callout to external service invocable actions before pausing a flow or scheduling an Apex queueable. For more information, contact your Salesforce administrator.

Then you need to add a ‘Wait’ element at some point before the call out.

The video below demonstrates what to do, but here are the key steps:

1. Add ‘Wait’ element before the HTTP Callout (“Wait for Conditions” type)
2. Leave the Default Path as is, for the other path choose:
   • Wait Conditions
     • Always Wait – No Conditions
   • Resume Event
     • Wait Until – A Specified Time
     • Time Source – Specific Time
     • Base Time – Running FLow Interview > CurrentDateTime
     • Offset Number – 0
     • Offset Unit – Hours
3. Save the change then your scheduled flow should have no problems performing the callout.

References

https://help.salesforce.com/s/articleView?id=platform.flow_considerations_trigger_schedule.htm&type=5
https://salesforce.stackexchange.com/questions/420689/flow-working-in-debug-mode-only-http-call-out