Just putting this out there: there is a known issue with the 10.12.5 update and SMB. After updating I can no longer connect to shares via SMB. Called in and spoke with Apple yesterday and they are aware. Engineers are working on it now. Our environment is AD so I was no longer getting the prompt for my credentials. It would never actually connect. One workaround was to put (smb://username:@server.domain.name/sharename)* in the connect to server window . This allowed me to connect but would not accept my password and eventually locked me out. Maybe it will work for you.
Question
FYI - 10.12.5 issues with SMB mounting
Enter your E-mail address. We'll send you an e-mail with instructions to reset your password.
