Third-Party Credentials Error

Hi All,

My On-premise Environment is installed with 18.4 version, In Admin Console when i'm creating the Third-Party Credentials, It is throwing me an error as

"Expression evaluation error [evaluation ID = 6D66LGYM] at function a!adminRouter: FATAL: The Appian data source cannot be reached. Access to the Appian data source is required. The Appian application will fail to deploy. Details: Cannot open connection".

Please find the error screenshot in the attachment.

Any help would be Appreciated.

Regards,

Krishna.