Execute the task in TransMac, then re-enable security shields immediately afterward. 3. Clear the Drive Structure with Diskpart
When attempting to flash a macOS DMG file to a USB flash drive on Windows using Acute Systems TransMac, encountering a or "could not access disk/media" error is a frequent issue. This error typically means Windows is blocking third-party software from gaining exclusive low-level block access to the storage device.
If you have the Windows Disk Management utility open, it frequently polls the drive status. Cloud Storage:
The USB drive has an existing, non-standard partition structure that Windows is struggling to relinquish control over. Proven Solutions to Unlock the Drive transmac drive has been locked by another program hot
Several factors can contribute to this error:
Re-open TransMac (right-click, Run as Administrator). 2. Disable Antivirus Temporarily
After digging around and testing several solutions, I finally resolved it. Here’s what causes this and how to properly fix it. Execute the task in TransMac, then re-enable security
Avoid front-case USB ports or external USB hubs, as they can cause power fluctuations and connectivity drops that trigger locks. Plug the drive directly into the motherboard ports at the back of your PC.
Right-click the name of the drive (on the left side where it says "Disk 1") or the volume bar on the right. Select Eject . Note: This forces Windows to release any handles it has on the drive.
If the drive is stuck in a read-only state or has hidden partitions from a previous macOS attempt, you need to wipe it clean at the command level. This error typically means Windows is blocking third-party
The simplest and most common fix is granting TransMac elevated system privileges. Without administrator rights, Windows will prioritize its own background services over third-party software. Close completely.
If you can tell me what you're trying to do with the drive (e.g., create a bootable USB, copy files), I can offer a more specific solution.
If the software remains blocked, identify the specific process holding the active lock using Microsoft PowerToys.
If you cannot delete the volume in Disk Management, you can force it using diskpart . Open Command Prompt as Administrator . Type diskpart and press Enter. Type list disk to find your USB drive number.
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