Make sure that you have the roles and permissions required for creating virtualized APIs as specified in Roles and Permissions Needed to Create and Manage Virtualized APIs.

Ensure that the webMethods Mediator is configured and running on the same machine webMethods Integration Server.

Applicable for OAuth2 scenarios. Ensure that the webMethods Mediator property watt.server.auth.skipForMediator is set to true. For details, see The watt.server.auth.skipForMediator Property.