RANCID (Really Awesome New Cisco confIg Differ) is a tool for automating the collection of hardware and configuration data from network devices. I recently upgraded an installation from version 2.3.1 to 2.3.8. And naturally, because I didn't have a ton of time to devote to this, stuff broke. It stopped pulling data from some switches. Not all switches, mind, that would be too easy to troubleshoot. Only some.
The last time I upgraded Net-SNMP it wasn't reporting the hrSystemProcesses OID. I wrote about that here. This time around I've upgraded to v5.7 and discovered two issues so far.