VNX LDAP configuration error: "Domain Settings update failed"

While using Unisphere GUI to save the LDAP settings for File on a new VNX box for authenticating to Microsoft AD, we were hit with the error - "Domain Settings update failed"

In case you are always frustrated by the lack of explanation like above, run this command in CLI to get a better idea on the error and possible ways to resolve:

nas_message -info <Message ID>

So for my error above, the results were:

nas_message -info 13693354005
MessageID = 13693354005
BaseID    = 21
Severity  = ERROR
Component = APL
Facility  = admindomain
Type      = STATUS

Brief_Description  = Domain Settings update failed.

Full_Description   = The domain settings could not be updated.

Recommended_Action = Issue could be due to errors in lockbox setting. a. Login to the control station CLI as root. b. Reset the lockbox with the following command. /nas/sbin/cst_setup -reset 

And running the command /nas/sbin/cst_setup -reset solved my problem and I was able to save the LDAP settings.