Once in a while Cisco releases a so-called Field Notice, and i’ve learnt that it’s a good idea to subscribe to those notifications because they can spare you a lot of trouble.
Usually a field notice means a bug so critical that it is imperative that you upgrade your devices as soon as humanly possible. The device may crash, die, steal your money, attempt to leave the data center and kill your relatives or worse.
You can subscribe to those notifications at https://cway.cisco.com/mynotifications . They will send you a validation email. Once you validate your email account, you will start getting notifications about bugs and field notices.
One example from this week was a FN for 3650, whose constant memory leaks meant that my SNMP manager kept creating tickets ”device lost”, because the device wasn’t responding to snmp polls.
A more flagrant example (a catastrophy, really) was the time where the clocks failed on ASAs after a certain time…