There are quite some possible reasons why you could be getting invalid_grant. See a list of likely causes below:
- The client_assertion used is expired.
- The client_assertion used is invalid.
- The client_assertion used is missing(not present) in the API call
See screenshot below :
Steps To Resolve:
- To fix this error ensure that you're appending the client_assertion to your connect/token API call.
- Validate the JWT generated correctly using the widget in our developer documentation or JWT.io.
- Ensure that the clientid used for the authorization and token endpoint matches the clientid used to generate the client_assertion.