If you’ve had your ear to the ground regarding the snapshot bugs/CBT bugs in vSphere lately you probably know that VMware discovered some issues in ESXi 6.0 Update 1 and, as a result, released ESXi 6.0 Update 1a. However, even after Update 1a a CBT (Changed Block Tracking) bug still presented itself causing all sorts of chaos relating to inconsistent incremental VM backups. Not good. The CBT bug can be referenced in KB 2136854. You’ll also find a link to the patch in that KB but here is a direct link as well.
Thankfully VMware is quick to dig into issues like this and have released Build 3247720 via the ESXi600-201511001 patch. You can apply this patch as you would any other (Update Manager, esxcli…). This is a recommended fix for anyone who is using snapshot-based backup solutions!