Having issues with the initiateGuestCheckoutSession API in production

[dh_972]

I am using trying to create Guest checkout order with sandbox credentials but it is alwasy giving thois error with any product I try "Your desired item(s) are not available for purchase at this time. The unavailability of an item could be for any of several reasons, including the item being out of stock. Add available item(s) and resubmit the call.", so I gave up and started trying with production APIs, but production API stragnly giving this error, any help on this, how to solve ?

{
    "errors": [
        {
            "errorId": 1100,
            "domain": "ACCESS",
            "category": "REQUEST",
            "message": "Access denied",
            "longMessage": "Insufficient permissions to fulfill the request."
        }
    ]
}

[midwayusa1]

Not sure if this will help but be sure to check the grant flow you're using.

The initiateGuestCheckoutSession method requires an access token with the client credential grant flow (Application Access Token) whereas the initiateCheckoutSession method requires an access token with the authorization code grant flow (OAuth User Access Token)