"The bless tool was unable to set the current boot disk" error in bootcamp macOS Sierra Problem: 

I can no longer boot Boot Camp partition (BCP) running Windows 10 Pro 1703. I am also unable to start Parallels 12.2.0 Virtual Machine based on the same BCP macOS side. Problem occurred suddenly without warning. I cannot isolate any action from user side that could have led to this situation. I did not try to resize partition. I would like to boot from internal BCP as I was able to a few hours ago if possible. I do have a backup saved disc image (WinClone 6) from a few weeks back and a backup I made after the issue began. I would like to avoid a solution where I have to clone BCP to external SSD and transfer it back to notebook.

Mac Notebook Specs:



diskutil list Output:



diskutil cs list Output:



Disk Utility Report:





Virtual Machine Output:



BCP is Not Visible at Startup (was few hours back)
BCP is Visible in Startup Disk in Preferences without
Paragon NTFS for Mac 15.0.828 installed (but cannot restart from BCP disk)
BCP is Not Visible in Startup Disk in Preferences with
Paragon NTFS for Mac 15.0.828 installed (but cannot restart from BCP disk using NTFS for Mac)
BCP is mountable/visible on Desktop 
Disk Utility not allowing me to verify/repair disk (grayed out/dimmed selection for applying First Aid to BCP)




Troubleshooting Steps:


HOLD ALT at Restart (x3) -> Only macOS partition visible
CMD+R (Recovery Mode) + Verify + BCP select restart -> "The bless tool was unable to set the
current boot disk"







ALT+CMD+R+P (Reset NVRAM) -> No resolution
Verify disk using Paragon NTFS for Mac 15.0.828 -> Success:





Repair disk using Paragon NTFS for Mac 15.0.828 -> Success:





ALT+CMD+R+P (Reset NVRAM) -> No resolution:





Google
Made post on stack exchange 
Made appt for Genius Bar


07/05/17 Update:

diskutil verifyDisk disk0:

Started partition map verification on disk0
Checking prerequisites
Checking the partition list
Checking the partition map size
Checking for an EFI system partition
Checking the EFI system partition's size
Checking the EFI system partition's file system
Checking the EFI system partition's folder content
Checking all HFS data partition loader spaces
Checking booter partitions
Checking booter partition disk0s3
Verifying file system
Checking Journaled HFS Plus volume
Checking extents overflow file
Checking catalog file
Checking multi-linked files
Checking catalog hierarchy
Checking extended attributes file
Checking volume bitmap
Checking volume information
The volume Recovery HD appears to be OK
File system check exit code is 0
Checking Core Storage Physical Volume partitions
Verifying storage system
Checking volume
disk0s2: Scan for Volume Headers
disk0s2: Scan for Disk Labels
Logical Volume Group CAF0EF87-18B3-429E-B956-071C41913E1E on 1 device
disk0s2: Scan for Metadata Volume
Logical Volume Group has a 24 MB Metadata Volume with double redundancy
Start scanning metadata for a valid checkpoint
Load and verify Segment Headers
Load and verify Checkpoint Payload
Load and verify Transaction Segment
Incorporate 0 newer non-checkpoint transactions
Load and verify Virtual Address Table
Load and verify Segment Usage Table
Load and verify Metadata Superblock
Load and verify Logical Volumes B-Trees
Logical Volume Group contains 1 Logical Volume
Load and verify ABA4E795-98B7-41CB-B45B-2A85180C8204
Load and verify C37D4F73-4CF7-4E22-BD12-732A22ECD7EA
Load and verify Freespace Summary
Load and verify Block Accounting
Load and verify Live Virtual Addresses
Newest transaction commit checkpoint is valid
Load and verify Segment Cleaning
The volume CAF0EF87-18B3-429E-B956-071C41913E1E appears to be OK
Storage system check exit code is 0
The partition map appears to be OK
Finished partition map verification on disk0


sudo fdisk /dev/disk0:
I was able to resolve macOS Sierra error about the bless tool by using the pictured setting on WinClone 6.0.3. I did not restore from winclone backup but rather just made my BCP bootable as an EFI instead of legacy BIOS drive. For some reason macOS started to view BCP as an unbootable legacy BIOS drive. My guess is installing Paragon suite of tools like NTFS, Hard Disk Manager, and ExtFS for Mac had this sudden and unintended result during the runtime environment. 



To prevent BSOD sysprep appears to be necessary when restoring WinClone backups on external drives.