Promise Reject not working

Summary:

Before save the workspace i am having one validation based on that i need to stop the workspace save action and i am using Promise for that . That reject is not working .

Content (required):

mySavingPromise.reject("Contact Mapped to this organization need to be In Active to terminate the organization");

Version (include the version you are using, if applicable):

Code Snippet (add any code snippets that support your topic, if applicable):