Spring Security OAuth - Provider Manager is Not Configured for Null Resource

The real reason is, you are using ResourceOwnerPasswordResourceDetails for a "client_credentials" access token request. We cannot interchange ResourceOwnerPasswordResourceDetails and ClientCredentialsResourceDetails.

In ClientCredentialsResourceDetails you need to set AccessTokenUri, ClientId, ClientSecret and grantType.In ResourceOwnerPasswordResourceDetails, you need to provide Username and Password along with AccessTokenUri, ClientId, ClientSecret and GrantType.

(Some authserver do accept password token request without username and password.. But I would say it is wrong)

Refer : Securing an existing API with our own solution

This is what i use:

@Beanpublic RestTemplate oAuthRestTemplate() {    ClientCredentialsResourceDetails resourceDetails = new ClientCredentialsResourceDetails();    resourceDetails.setId("1");    resourceDetails.setClientId(oAuth2ClientId);    resourceDetails.setClientSecret(oAuth2ClientSecret);    resourceDetails.setAccessTokenUri(accessTokenUri);    OAuth2RestTemplate restTemplate = new OAuth2RestTemplate(resourceDetails, oauth2ClientContext);    return restTemplate;}

The correct headers will be set bij the framework, but the username/password will be base64 encodes as Authorization header (basic authentication). This is the OAuth2 spec for a client_credentials grant.

Check if the api supports the spec:

curl -X POST \'https://api.app.com/v1/oauth/token' \-i -u 'client:secret' \-H 'Content-Type: application/x-www-form-urlencoded' \-d 'grant_type=client_credentials'

If you need to send the username & password as data instead of authorisation header, you can add resourceDetails.setAuthenticationScheme(AuthenticationScheme.form); this should set de username & password as data

This could be oocured beacuse server doest not recognize the content type you posting to that specific url. In your CURL request try include the 'content-type: application/x-www-form-urlencoded' for custom conrtroller using http headers.

Also you have not set username and password for resourceDetails.resourceDetails.setUserName("user");resourceDetails.setUserName("password");

if those does not work try to extract the request that Encoded with application/x-www-form-urlencoded and pass it as a string via RestTemplate and you can get the token.

Let me know any if you need additional support.

Try the code below that is giving token as and string response.