(gcloud.preview.app.deploy) Unexpected error. Expanded version

I am trying to update my managed vm using the command:

gcloud preview app deploy app.yaml --set-default --version "tacos"

      

        
        
        
      

    

This works fine and suddenly it throws:

ERROR: (gcloud.preview.app.deploy) Unexpected Error. Deployed Version: tacos.384484674339405112

      

        
        
        
      

    

Any idea why? Thank!