eBay API Access Token Issue: The requested scope is invalid, unknown, malformed, or exceeds the scope granted to the client

Question

I'm working with the eBay API and encountering an issue during the OAuth process. I'm trying to receive an access_token through this URL https://api.sandbox.ebay.com/identity/v1/oauth2/token

I'm making a POST with this data (please, also, see the Postman screenshot below):

- Headers: 
  - Content-Type: `application/x-www-form-urlencoded`
  - Authorization: <Base64 encoded client ID and secret>
- Body (x-www-form-urlencoded):
  - grant_type: client_credentials
  - scope: https%3A%2F%2Fapi.ebay.com%2Foauth%2Fapi_scope https:%3A%2F%2api.ebay.com%2oauth%2api_scope%2sell.account
  - redirect_uri: <My redirect URL>

After making the POST request, I get the following response:

{
    "error": "invalid_scope",
    "error_description": "The requested scope is invalid, unknown, malformed, or exceeds the scope granted to the client"
}

Answer 1

You mixed a scope "Authorization Code Grant Type" and " Client Credential Grant Type" even if you assigned "grant_type" is "client_credentials"

Authorization Code Grant Type

https://api.ebay.com/oauth/api_scope/sell.account

Client Credential Grant Type

https://api.ebay.com/oauth/api_scope

So have to use same "Client Credential Grant Type" scopes

I demo two same category scopes from "Client Credential Grant Type"

https://api.ebay.com/oauth/api_scope https://api.ebay.com/oauth/api_scope/buy.guest.order

Username and Password copy from your Application Keys (client id and client secret) - the following image.

You can get the scope list from here

https://developer.ebay.com/my/keys

Client Credential Grant Type

Scope	Heading Description
https://api.ebay.com/oauth/api_scope	View public data from eBay
https://api.ebay.com/oauth/api_scope/buy.guest.order	Purchase eBay items anywhere without signing in to eBay
https://api.ebay.com/oauth/api_scope/buy.item.feed	View curated feeds of eBay items
https://api.ebay.com/oauth/api_scope/buy.marketing	Retrieve eBay product and listing data for use in marketing merchandise to buyers
https://api.ebay.com/oauth/api_scope/buy.product.feed	View curated feeds of products from the eBay catalog
https://api.ebay.com/oauth/api_scope/buy.marketplace.insights	View historical sales data to help buyers make informed purchasing decisions
https://api.ebay.com/oauth/api_scope/buy.proxy.guest.order	Purchase eBay items anywhere, using an external vault for PCI compliance
https://api.ebay.com/oauth/api_scope/buy.item.bulk	Retrieve eBay items in bulk
https://api.ebay.com/oauth/api_scope/buy.deal	View eBay sale events and deals

Authorization Code Grant Type

Scope	Heading Description
https://api.ebay.com/oauth/api_scope	View public data from eBay
https://api.ebay.com/oauth/api_scope/buy.order.readonly	View your order details
https://api.ebay.com/oauth/api_scope/buy.guest.order	Purchase eBay items anywhere without signing in to eBay
https://api.ebay.com/oauth/api_scope/sell.marketing.readonly	View your eBay marketing activities, such as ad campaigns and listing promotions
https://api.ebay.com/oauth/api_scope/sell.marketing	View and manage your eBay marketing activities, such as ad campaigns and listing promotions
https://api.ebay.com/oauth/api_scope/sell.inventory.readonly	View your inventory and offers
https://api.ebay.com/oauth/api_scope/sell.inventory	View and manage your inventory and offers
https://api.ebay.com/oauth/api_scope/sell.account.readonly	View your account settings
https://api.ebay.com/oauth/api_scope/sell.account	View and manage your account settings
https://api.ebay.com/oauth/api_scope/sell.fulfillment.readonly	View your order fulfillments
https://api.ebay.com/oauth/api_scope/sell.fulfillment	View and manage your order fulfillments
https://api.ebay.com/oauth/api_scope/sell.analytics.readonly	View your selling analytics data, such as performance reports
https://api.ebay.com/oauth/api_scope/sell.marketplace.insights.readonly	View product selling data to help you make pricing and stocking decisions
https://api.ebay.com/oauth/api_scope/commerce.catalog.readonly	Search and view eBay product catalog information
https://api.ebay.com/oauth/api_scope/buy.offer.auction	View and manage bidding activities for auctions
https://api.ebay.com/oauth/api_scope/commerce.identity.readonly	View a user's basic information, such as username or business account details, from their eBay member account
https://api.ebay.com/oauth/api_scope/commerce.identity.email.readonly	View a user's personal email information from their eBay member account.
https://api.ebay.com/oauth/api_scope/commerce.identity.phone.readonly	View a user's personal telephone information from their eBay member account
https://api.ebay.com/oauth/api_scope/commerce.identity.address.readonly	View a user's address information from their eBay member account
https://api.ebay.com/oauth/api_scope/commerce.identity.name.readonly	View a user's first and last name from their eBay member account
https://api.ebay.com/oauth/api_scope/commerce.identity.status.readonly	View a user's eBay member account status
https://api.ebay.com/oauth/api_scope/sell.finances	View and manage your payment and order information to display this information to you and allow you to initiate refunds using the third party application
https://api.ebay.com/oauth/api_scope/sell.payment.dispute	View and manage disputes and related details (including payment and order information)
https://api.ebay.com/oauth/api_scope/sell.item.draft	View and manage your item drafts
https://api.ebay.com/oauth/api_scope/sell.item	View and manage your item information
https://api.ebay.com/oauth/api_scope/sell.reputation	View and manage your reputation data, such as feedback
https://api.ebay.com/oauth/api_scope/sell.reputation.readonly	View your reputation data, such as feedback
https://api.ebay.com/oauth/api_scope/commerce.notification.subscription	View and manage your event notification subscriptions
https://api.ebay.com/oauth/api_scope/commerce.notification.subscription.readonly	View your event notification subscriptions
https://api.ebay.com/oauth/api_scope/sell.stores	View and manage eBay stores
https://api.ebay.com/oauth/api_scope/sell.stores.readonly	View eBay stores