Here are the common problems that can make a volume inaccessible: So, why CHKDSK can't open a volume for direct access is clear: Either another program is accessing the target volume at present, or the target volume itself is inaccessible.

However, CHKDSK's characteristic of exclusive access often prevents it from getting the access privilege. Then, if the system permits, CHKDSK can read and write data on the volume otherwise, it can't do that. Usually, when CHKDSK wants to access a volume, it needs to request the access privilege first. How to Fix Hard Drive Issues with CHKDSK (For Beginners) Common reasons for 'Cannot open volume for direct access' error.