Azure durable functions sample says sync functions are not allowed

forget the last sentence of my comment above regarding reverting to version 2.

I have changed my runtime version to version 2 and this time the HTTP Trigger was successful in running. To change the runtime version, I clicked on the "Function App settings" link underneath the Configured features heading on the Overview tab of the durable function I created

In the Function app settings tab, I selected the ~2 button to change the runtime version to 2.0.xxxx

Also, just to make sure the durable functions package was installed, I ran

npm view durable-functions