Fix Media Creation Tool Error 0x80042405 0xa001b

If you see error code 0x80042405 0xa001b (or its close relative 0x80070002 0xa001b) while using the Windows Media Creation Tool, the fix is to clear the tool’s temporary files, free up drive space, and ensure your USB drive is properly formatted and connected. This error typically appears during the download or writing phase of creating Windows installation media, and it usually means the tool cannot write to its cache or to the USB drive.

What the Error Codes Mean

These hexadecimal codes are not random. They come from two different sources combined into one message:

0x80042405 – This is a Windows Update–related error that often translates to WU_E_DM_URLNOTAVAILABLE or a download manager failure. In the context of the Media Creation Tool, it indicates a problem with downloading or accessing the Windows installation files.
0x80070002 – This is the classic ERROR_FILE_NOT_FOUND code. The tool is looking for a file that isn’t there, often because a previous download was incomplete or the temporary folder was cleaned.
0xa001b – This is a Microsoft-defined error specific to the Media Creation Tool. It generally points to a failure while writing to the USB device or while accessing the tool’s own working directory.

When you see the combined code, it almost always means the tool cannot complete the file transfer, either because it ran out of space, lost access to the drive, or the download cache became corrupted.

Why the Media Creation Tool Fails

The Media Creation Tool works in two phases. First, it downloads the Windows installation files (several gigabytes) to a temporary folder on your PC. Second, it formats your USB drive and copies those files over. A failure in either phase can trigger the error.

Common root causes include:

Insufficient disk space – The tool needs at least 8 GB free on your system drive for the download, plus the full size of the USB drive you’re using.
Antivirus or security software – Some security programs quarantine the downloaded files or block the tool from writing to the USB drive.
Corrupted temporary files – If a previous attempt was interrupted, the leftover files can confuse the tool.
USB drive issues – A faulty port, a failing drive, or a drive with an incompatible file system can stop the write process.
Network instability – A dropped connection during the download can leave incomplete files.

Step-by-Step Fixes

Try these in order. The first fix resolves most cases.

Clear the tool’s temporary folder. Press Win + R, type %temp%, and press Enter. Delete everything inside (skip files that are in use). Also delete the folder C:\Windows\SoftwareDistribution\Download contents if you have admin rights. This removes corrupted download remnants.
Free up space on your system drive. The tool needs at least 8–10 GB free. Use Disk Cleanup or Settings > System > Storage to remove temporary files.
Reformat your USB drive. Insert the USB stick, open File Explorer, right-click the drive, choose Format, select FAT32 (for UEFI systems) or NTFS (for legacy BIOS), and perform a full format. Then try the tool again.
Use a different USB port. Prefer a USB 2.0 port on the back of a desktop. Avoid hubs and front-panel ports that may have power issues.
Temporarily disable antivirus. Pause real-time protection from your security software, run the tool, then re-enable it. Do not disable Windows Defender’s core features.
Run the tool as administrator. Right-click the Media Creation Tool executable and select Run as administrator. This ensures it can write to protected folders.
Download the ISO instead. If the USB creation keeps failing, use the tool’s option to download an ISO file to your hard drive. Then use a separate utility like Rufus to write the ISO to USB. This bypasses the tool’s USB-writing logic.

If the Error Persists

When none of the above work, the problem may be deeper:

Check the USB drive health. Try a different USB stick. Many cheap drives fail silently during large writes.
Check your system drive for errors. Open an elevated Command Prompt and run sfc /scannow to repair system files. Then run chkdsk C: /f (you may need to restart).
Disable the download cache. Some users report success by setting the environment variable MCT_DOWNLOAD_CACHE to a different drive with plenty of space. This is not officially documented, but it forces the tool to use a clean folder.
Use the Windows Installation Assistant. If you’re upgrading the current PC (not creating media for another PC), the Windows Installation Assistant uses a different download mechanism and often avoids this error.

Preventing the Error in Future Attempts

Once you get the tool working, these habits reduce the chance of a repeat:

Always use a USB drive with at least 8 GB capacity and no important data on it.
Close all other applications during the download to avoid interruptions.
Keep your system drive free of clutter – the tool needs room for temporary files.
If you’re on a laptop, keep it plugged in to avoid power-saving USB suspension.

Frequently Asked Questions

Will this error damage my USB drive?

No. The error occurs before or during the write process, and it doesn’t cause physical damage. However, if the drive is old or faulty, repeated failed writes can expose existing issues. After the error, reformat the drive and test it with another file copy to confirm it works.

Can I use the same USB drive after the error?

Yes, but you must reformat it first. The Media Creation Tool may leave a partial partition structure that confuses future attempts. A full format (not quick format) clears everything and gives you a clean slate.

Does the error mean my Windows license is invalid?

No. This error is purely about file transfer and storage. It has nothing to do with your product key or activation status. You can still use the tool once the storage issue is resolved.

Why does the error sometimes appear at 99%?

This happens when the tool finishes downloading but fails to write the final boot files to the USB. It’s usually a USB issue – either the drive dropped off the bus or the file system became corrupted. Reformatting and using a different port often fixes it.

Is there a way to skip the USB and use a DVD instead?

Yes. The Media Creation Tool offers an ISO download option. You can burn that ISO to a DVD using Windows’ built-in burner (right-click the ISO and select Burn disc image). DVDs are more forgiving of write errors, though they hold less data and are slower.

Should I try the tool on a different computer?

If you have access to another PC, trying it there is a good diagnostic step. If it works on the other machine, the problem is likely your local environment – antivirus, disk space, or system file corruption. If it fails on both, the issue is with the USB drive or the tool’s download servers.

General steps for current mainstream versions; menus can differ by device and version. See the disclaimer or report an error.

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