is not a valid certificate thumbprint. Certificate thumbprint should contain 40 hexadecimal characters. To generate the certificate ...

'{0}' is not a valid certificate thumbprint.
Certificate thumbprint should contain 40 hexadecimal characters.
To generate the certificate and install it to My store, execute the following command: TfsAzureCert CreateApiCert -f TfsApiCert.cer
To associate a certificate with your subscription, login to the Windows Azure Portal, select your project, click on Account tab and navigate to Manage My Certificates. Upload the .cer file that is associated with your certificate to the Portal.