One day, I supported a workshop for Amazon SageMaker, obviously, Ground Truth is part of the course and we taught how users can leverage Ground Truth to label their data.

Participants were guided to setup their Private Workforce in Ground Truth, but somehow an user reported that they neither receive the invitation mail which is sent from Ground Truth to provide a temporary password for the workers to start the labeling job nor get the password reset mail.

The first idea comes to my mind is to rebuild Cognito User Pool for Ground Truth Private workforce, and I try to delete the Cognito User Pool without any problems on Cognito service page.

However, when I went back to Ground Truth UI, I got this error “400 ResourceNotFoundException: User pool ap-northeast-1_0mDKPv4vW does not exist. Request ID: 2cd94004-91a3-4d70-b98c-6b15c5c723cb”. I can’t create a new User Pool or delete the private workforce to rebuild a new one on the UI.

I try to google and search it on stackoverflow, and I can see some answers about Cognito itself but it has no clue on how to fix this problem for Ground Truth. I even start to think whether I need to create a support ticket to seek the help from support engineer.

Finally, I know how to fix the issue, and it’s not that difficult to resolve it. Ground Truth UI doesn’t provide this kind of function to let you delete the default workforce, and you can do nothing there. BUT you can achieve this through AWS CLI.

aws sagemaker delete-workforce --workforce-name default

This cleans your slate and you should create a new work team to continue !