Hi,
I have attempted to use headless identity APIs as per https://help.salesforce.com/s/articleView?id=sf.remoteaccess_authcodecreds_singlepageapp.htm&type=5
I have created the Connected app and checked the Enable Client Credentials Flow as well as assigned the Run As API Only user.
When I call my site authroize endpoint (.....abcde.sandbox.my.site.com/services/oauth2/authorize) = I get the following:
Invalid URL
The requested URL "[no URL]", is invalid.
Reference #9.88d11102.1684329647.8976a77f
Any idea why my Authroize endpoint is returning 400 Bad Request?
My callback URL for the connected app and my redirectURI in the callout is - ....abcde.sandbox.my.site.com/services/apexrest/code/extraction - as per the example.
#Headless Identity
Jonathan Fox (Cooper Parry) 
Forum Ambassador
It appeared that going to sleep and doing nothing fixed it. I suspect one of the settings in this org took some considerable time to propagate through the Salesforce servers.
