Data collection fails for certain vCenter Servers which were upgraded from version 4.0 and below.
The version of Java shipped with Virtualization Manager version 6.1.1 and later rejects connections to vCenter Servers which are using RSA certificates shorter than 1024 bits. Even though vCenter Server uses 2048-bit certificates by default since version 4.1, these certificates are not regenerated when the system is updated. As a result, data collection from vCenters which were updated from version 4.0 and below fails.
Option 1 (Recommended): Regenerate the certificates
See the following KB article at the VMware website for instructions about how to check the length of the certificate and how to regenerate it:
Option 2: Modify the Java security settings to allow certificates with short RSA keys