3588578 - "HTTP OAUTH 2.0 RESOURCE OWNER PASSWORD CREDENTIALS GRANT " call is failing with response code: 400

The call to retrieve token using PI is is failing in REST receiver, however using POSTMAN, the call is successful.

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In the XPI 50 or 100 you can find one the below errors:

Error while processing Authorization request!
[EXCEPTION]
com.sap.aii.adapter.rest.ejb.common.exception.HttpCallException: HTTP OAUTH 2.0 RESOURCE OWNER PASSWORD CREDENTIALS GRANT call to https://<target:port>/oauth2/v0/token not successful. Error while obtaining authorization code - response code: 400
response:
"Received vectorized value :grant_type=[\"password\" \"password\"]"
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Transmitting the message to endpoint <local> using connection SOAP_http://sap.com/xi/XI/System failed, due to: com.sap.engine.interfaces.messaging.api.exception.MessagingException: com.sap.aii.adapter.rest.ejb.common.exception.HttpCallException: HTTP OAUTH 2.0 RESOURCE OWNER PASSWORD CREDENTIALS GRANT call to https://<target:port>/oauth2/v0/token not successful. Error while processing Authorization request!

SAP Netweaver 7.5

PI, PO, Netweaver 7.5, Authorization request, Rest, HTTP OAUTH 2.0 RESOURCE OWNER PASSWORD CREDENTIALS GRANT, response code: 400 , KBA , BC-XI-CON-RST , Rest Adapter , Problem