Type list disk and find the disk number for your USB drive (check the size carefully!).
Creating a macOS bootable installer on Windows is a lifesaver, but seeing the or "Drive is locked by another program" error in TransMac can bring your progress to a halt. This usually happens because Windows is protecting the drive from the low-level changes TransMac needs to make.
If TransMac continues to throw lock errors due to system environment conflicts, specialized image-burning programs offer alternative workflows: Best Used For Operating System Straightforward DMG to USB burning Windows / macOS / Linux Rufus Advanced partition configuration UUByte DMG Editor Native macOS installation building Share public link
If you are trying to create a bootable macOS USB drive on a Windows PC, you have likely turned to TransMac. It is one of the most popular utilities for opening Mac APFS or HFS+ formatted drives on Windows. However, users frequently encounter a frustrating error message when trying to write to or format a USB drive:
Once the drive shows as "Unallocated," close Disk Management and try TransMac again. 6. Use Diskpart to Clear the Drive (Advanced) transmac drive has been locked by another program hot
: Other partition managers or disk monitoring utilities can block access. Troubleshooting Steps
Now, open TransMac. The drive should no longer have a drive letter in Windows, but TransMac can still access it via physical disk number. Try your operation again.
TransMac requires elevated system privileges to override third-party software locks and write directly to disk sectors. Right-click the desktop icon. Select Run as administrator . Click Yes on the User Account Control (UAC) prompt. Attempt to format or write your .dmg file again. 3. Clear and Clean the USB Drive via Diskpart
Wipe all existing volumes, partition maps, and formatting data: clean Use code with caution. Type list disk and find the disk number
The "Lock" isn't a physical switch or a broken drive; it’s a software tug-of-war. By running TransMac with Administrative privileges and using the
Check your computer’s BIOS/UEFI settings to ensure there are no strict security settings preventing writes to USB devices. 5. Format on a Mac (If Available)
: Ensure you are running TransMac with full administrative privileges by right-clicking the application and selecting Run as administrator Disable Security Software : Temporarily disable Windows Defender Real-time Protection
: If you have the DMG or ISO file currently mounted as a virtual drive in Windows, right-click the virtual drive in File Explorer and select Advanced Solution: Diskpart Clean If the drive remains locked, use the Windows utility to force-clear any existing partitions and locks. Warning: This will erase all data on the USB drive. Start Menu , right-click it, and select Run as administrator and press Enter. If TransMac continues to throw lock errors due
Type select disk X (replace with your specific USB drive number).
Once completed, close the Command Prompt, unplug the USB drive, plug it back in, and open TransMac. 5. Stop the Windows Search and Storage Service
Press Win + R , type cmd , and press Ctrl + Shift + Enter to open as Administrator. Type diskpart and press Enter. Type list disk to view all drives.
Type select disk X (replace X with your actual USB drive number). Type clean and press Enter to wipe the partition data. Type convert gpt if creating a modern macOS bootable drive.