403 Forbidden

The request sent to the server was formed correctly and authorization parameters were valid but the target server refused it.

Possible solutions

Make sure you are authorized to access the resources you are requesting.
Check if you have the appropriate rights granted to fetch/change resources.
In case of calls that use OAuth and access token, make sure that the right scopes are requested or end-user accepted consent, requested by the client application.
For example, If a call tries to fetch an account that doesn't belong to the customer who is authenticated via OAuth, 403 error code will be returned.