I received "D:\ is not accessible. Access is denied" - How to fix it?

Maggie

When I try to open my D drive, I get the following error message:
“D:\ is not accessible. Access is denied.”

I don’t know why this happens. I want to fix it quickly because I urgently need the files on the disk. I’m working on a Windows 10 PC. My C drive can open normally while D drive not. I have tried several times to access it but failed each time.

I don’t want to format my D drive because it contains my important files. Is there a better way?

715y

Maggie To understand why this happens without panic: the "Access is denied" error on a logical volume like D:\ usually boils down to a corruption of the ACL (Access Control List) or the MFT (Master File Table) entries parsing the security descriptors. When you double-click the drive, Windows executes an API call (CreateFile or FindFirstFile). If the Security Identifier (SID) in your current user token doesn't match the entries in the DACL (Discretionary Access Control List) assigned to the root directory of that volume, the OS kernel explicitly blocks the I/O request.

As the first reply mentioned, this often happens after a major Windows update shifts local SID mappings, or a dirty unmount (sudden power off) flags the volume's dirty bit, causing the NTFS driver to misread security descriptors. Since your hardware is likely fine, your data is completely safe underneath this logical software barrier.

enlh

Maggie Windows 10 updating itself and instantly deciding that you don't own your own data is peak Microsoft. It’s like coming home and your front door telling you, "Sorry, I don't recognize your face, please format your house."

Whatever you do, do NOT click that tempting "Format disk" pop-up that Windows loves to spam when it gets confused. That's the tech equivalent of burning down the house because you lost the keys. Follow the permission fixes or use the command line.

bcyk

Maggie I see this at least three times a week in the shop. 90% of the time it's just a borked NTFS permission chain, but there's a 10% chance the drive developed bad sectors right where the system index files sit, forcing Windows to mount it as RAW or unreadable.

Before you mess with the security settings, let’s rule out file system corruption.

Right-click the Start menu and select Command Prompt (Admin) or Windows PowerShell (Admin).

Type chkdsk D: /f and hit Enter.

If it says "The type of the file system is NTFS" and fixes some indexes, try opening the drive. If it says "The type of the file system is RAW", stop immediately. Do not try the permission fixes from floor 1, because there are no permissions left to fix—the index is gone, and you’ll need recovery software. Try CHKDSK first and report back what it says.

Edadewb-11

Sounds like a permissions issue. It's almost certainly just Windows getting confused about permissions after an update or a weird shutdown. Since your C drive is fine and you want to avoid formatting, the good news is that your data is likely still there; Windows just isn't letting you "through the door" right now.

Try this, it usually does the trick:

Open This PC, right-click on your D: drive, and select Properties.
Go to the Security tab and click Advanced.
Look for the Owner section at the top and click Change.
In the box, type your current Windows username (or just type Everyone), click Check Names, and then click OK.
Crucial: Check the box that says "Replace owner on subcontainers and objects" before clicking Apply.

If that doesn't work, go back to the Security tab, click Edit, then Add. Type in Authenticated Users and give them Full Control. I've seen cases where a Windows update tweaks security IDs, and adding this group acts like a master key.

Let me know if this works for you!

obtr

Edadewb-11 Giving "Everyone" or "Authenticated Users" Full Control over the root of a secondary partition is a massive security risk and a lazy band-aid solution. If this machine is ever compromised or shared, you've just blasted open the permissions for any malicious script to execute or modify files on D:\ without UAC elevation.

OP, if you are going to take ownership via the GUI as suggested above, type Administrators (with an 's') instead of "Everyone". This restricts root-level full control to the local administrators group, which your account should already belong to. Also, the GUI method frequently hangs on large drives if it encounters a single corrupt system file. If the GUI throws an error halfway through, you'll need to drop into an elevated Command Prompt and force it via CLI.

savl

Edadewb-11 Fascinating. Saved this thread because my external backup drive did this exact same thing last month and I ended up formatting it out of pure frustration. Wish I had seen this security tab workaround earlier. Upvoted for visibility, hope OP gets their files back.

715y

savl A necessary caveat to the chkdsk approach: while running chkdsk /f is practical, if the underlying issue is actually failing hardware (magnetic degradation or NAND flash exhaustion), running a heavy write-correct operation like CHKDSK can put immense stress on the drive, potentially causing the drive controller to lock up permanently.

If OP hears any clicking noises or notices extreme system lag when trying to access D:\, they should avoid CHKDSK entirely. In a true critical data scenario, the absolute safest sequence is: bit-stream clone the drive sectors to an image file first, then perform logical repairs on the clone. If it's purely a silent SSD or a healthy HDD, CHKDSK is a reasonable diagnostic step.

obtr

savl Exactly. And if CHKDSK confirms it is NTFS and the issue is strictly permissions, using the GUI to change ownership (as Floor 1 suggested) is incredibly inefficient. It takes ages.

OP, if CHKDSK runs clean, use icacls. It's cleaner, faster, and doesn't get stuck in GUI loops. Open Admin CMD and run these two commands:

takeown /f D:\ /a /r /d y

icacls D:\ /grant administrators:F /t /c /q

The first command forces ownership back to the local Administrators group recursively. The second grants Full Control (:F) while ignoring errors (/c) and running silently (/q). This is the proper, scalable way to reset a volume's DACL.

enlh

715y Ah, yes, command line utilities with cryptic syntax flags—the ultimate way to make OP feel like a 90s movie hacker just to open their homework folder.

But seriously OP, listen to the terminal wizards here. Copy-pasting those two lines into a black box is infinitely better than clicking "Next", "Apply", and "OK" through fifty nested Windows 10 settings menus that look like they were designed by three different committees who hated each other.

savl

715y Wow, those command line strings look powerful. Just to be sure, if I run that icacls command on my own drive in the future, does it delete any actual data? Or does it literally just overwrite the "lock" on the folders? Sorry if this is a dumb question, just trying to learn.

bcyk

enlh Not a dumb question at all. No, icacls and takeown do not touch your actual data files (your photos, docs, videos, etc. remain completely untouched). Think of your drive like a massive filing cabinet. Your files are inside the folders. What these commands do is simply swap out the rusty padlocks on the outside of the cabinet drawers and hand you a master key.

Let's wait for OP to tell us if the drive is recognized as NTFS or RAW so we can give them the final push across the finish line.