"Internal error" every time I snapshot, delete old snapshot(s), and reclaim disk space.

Hello.

I am using VMware Fusion Pro v8.0.2 (also reproduced in v8.0.1) with a couple months old updated 64-bit W7 EE SP1 VM from VMware Fusion v7.1.x in my work's 15" MacBook Pro (early 2013; Retina) with updated Mac OS X v10.10.5 (Yosemite). I noticed a pattern every time I use VM to update its softwares like Windows updates with their required reboots, shut down, take a snapshot, delete the old snapshot(s), and then reclaim the disk space. After all that, VMware Fusion gave me a pop-up error dialog box saying "Internal Error".

I boot up the VM and don't see anything wrong. Why do I keep seeing this error? Thank you in advance.