You have landed up in a familiar situation looks like.
This error comes when VMware Snapshots are getting failed. So when SMVI is invoking VMware to take VMWare consistent snapshot they are failing.
Since you have enabled VMware consistent snapshot during the backup profiling ( this is by-default and best practice to do), you are seeing this.
Try taking a backup disabling that and see if the error persists.
Also, for VMware snapshot issue try taking a VMware snapshot directly from the VI server. ( for online VM. I'm pretty sure this will fail).
You need to go thorugh couple of VMware articles for this :
Best solution is simply to re-install VMware Tools on those VM machines. ( I hope you have installed that previously )
All the Best !!!