ReadyBoost caches USB drive space to act as RAM. But when ReadyBoost is enabled (or was enabled in the past), it leaves a driver lock on the device.
The "Rufus access to device denied" error on Windows 7 is rarely a hardware problem. In 90% of cases, it is caused by a stale Explorer lock, a legacy driver filter, or an antivirus interceptor. By methodically working through Solutions 1 (Kill Explorer) and 2 (DiskPart Clean), you will resolve the issue for most standard USB drives.
For persistent cases, the registry filter cleanup (Solution 6) or a temporary downgrade to Rufus 3.22 is your best bet. Windows 7 is an unsupported operating system as of January 2020, and its driver stack is increasingly incompatible with modern peripheral tools. However, with the fixes outlined above, you can continue using Rufus effectively for legacy bootable media creation.
Final advice: If you rely on Rufus daily, consider upgrading your workflow to Windows 10 or 11 on a secondary machine for USB creation. But for those who must stay on Windows 7, this guide is your definitive resource for conquering the "access denied" error.
In Windows 7, the "Access to the device is denied" error in Rufus usually means another program is blocking Rufus from getting exclusive control of your USB drive. Quick Fixes Run as Administrator : Right-click the Rufus file and select Run as administrator Move the ISO File : Ensure your Windows 7 ISO file is rufus access to device denied windows 7
stored on the same USB drive you are trying to format. Move it to your desktop or C: drive before starting. Disable Antivirus
: Security software or "Controlled Folder Access" might be "locking" the drive. Temporarily disable your antivirus or real-time protection and try again. Close File Explorer
: Make sure you don't have any folders from the USB drive open in Windows Explorer, as this can create a "sharing violation". Advanced Troubleshooting
If the basic fixes don't work, try these deeper system adjustments: ReadyBoost caches USB drive space to act as RAM
Rufus is a popular utility for creating bootable USB drives. On Windows 7, you may encounter "Access to the device is denied" immediately after clicking Start or during the formatting/writing process.
What causes this?
If possible:
If domain-enforced policy denies access, override is not possible without admin rights. In standalone systems, set:
Computer Config → Admin Templates → System → Removable Storage Access → All Removable Storage: Deny write access → Disabled. The "Rufus access to device denied" error on
A step-by-step diagnostic approach was tested on 25 Windows 7 SP1 machines exhibiting the error.
Windows 7’s generic USB driver (usbstor.sys) can become corrupted.
To Update:
To Rollback (if you recently updated drivers):