How to Fix Windows 11 ISO Stuck at 99% Download

If your Windows 11 ISO download gets stuck at 99% and never finishes, you are not alone. This issue usually happens because of corrupted cache files, interrupted network sessions, browser conflicts, Windows Update service glitches, or damaged system files.

You can easily fix this without restarting the entire download in most cases. This guide walks you through proven solutions — from quick checks to advanced system repairs — so you can complete the ISO download safely and move forward with installation or upgrade.

Step 1 – Wait 10–15 Minutes and Check Disk Activity

Sometimes the progress bar freezes visually while the system continues working in the background.

What to do:

1. Open Task Manager → Performance tab.
2. Check Disk usage and Network activity.
3. If disk activity remains high, wait another 10–15 minutes.

If disk and network activity stay near zero for more than 15 minutes, proceed to the next fix.

Step 2 – Pause and Resume the Download

A paused network stream often resumes correctly and finishes the last few megabytes.

How:

• Open your browser’s download manager.
• Click Pause → wait 10 seconds → click Resume.

If the download resumes and completes, verify the file size before use.

Step 3 – Check Free Disk Space

The ISO requires extra temporary space during verification.

Recommended:

• Keep at least 30 GB free space on the drive storing the ISO.

How to check:

1. Open This PC.
2. Right-click your drive → Properties.
3. Confirm sufficient free space.

If space is low, delete temporary files or move large files to another drive.

Step 4 – Clear Browser Cache and Retry Download

Corrupted browser cache frequently causes stalled downloads.

Chrome / Edge:

1. Press Ctrl + Shift + Delete.
2. Select Cached images and files.
3. Click Clear data.
4. Restart the browser and reattempt the download.

If possible, try downloading using a different browser to eliminate profile conflicts.

Step 5 – Reset Windows Update Services and Cache

Windows background services sometimes lock temporary files used during ISO validation.

How:

1. Open Command Prompt as Administrator.
2. Run the following commands one by one:

net stop wuauserv
net stop bits
net stop cryptsvc
ren C:\Windows\SoftwareDistribution SoftwareDistribution.old
ren C:\Windows\System32\catroot2 catroot2.old
net start wuauserv
net start bits
net start cryptsvc

3. Restart your PC.
4. Retry the ISO download.

This clears corrupted update cache safely.

Step 6 – Run Windows Update Troubleshooter

The built-in troubleshooter automatically repairs common service issues.

How:

1. Open Settings → System → Troubleshoot → Other troubleshooters.
2. Run Windows Update Troubleshooter.
3. Apply any suggested fixes.
4. Restart your PC and retry the download.

Step 7 – Repair System Files Using SFC and DISM

Corrupted system files may block download completion.

How:

1. Open Command Prompt as Administrator.
2. Run:

sfc /scannow

3. After completion, run:

DISM /Online /Cleanup-Image /RestoreHealth

4. Restart your PC and retry the ISO download.

Step 8 – Temporarily Disable Antivirus or Firewall

Security software sometimes blocks large file verification.

What to do:

• Temporarily disable third-party antivirus protection.
• Retry the ISO download.
• Re-enable protection after completion.

Do not keep security disabled longer than necessary.

Step 9 – Use a Direct ISO Download Instead of Media Creation Tool

If the Media Creation Tool repeatedly stalls, download the ISO directly from Microsoft using your browser.

This avoids background service dependency and improves stability.

Step 10 – Verify ISO Integrity After Download Completes

A corrupted ISO may fail during installation even if the download completes.

How:

1. Open PowerShell.
2. Navigate to the ISO folder:

cd "C:\YourISOFolder"

3. Run:

Get-FileHash YourISOFile.iso

4. Compare the hash with Microsoft’s published checksum.

If hashes match, the file is safe to use.

When to Restart the Download Completely

Restart the download only if:

• The file size stops changing permanently
• Resume fails repeatedly
• Hash verification fails
• File shows incomplete size

Use a wired network connection for best reliability.

FAQs

Why does Windows 11 ISO freeze at 99%?

The system verifies file integrity at the final stage. Cache corruption, disk space issues, antivirus interference, or service conflicts commonly cause the stall.

Can I safely cancel a stuck ISO download?

Yes. Cancel only after confirming no disk or network activity for at least 15 minutes.

Will restarting damage my PC?

No. Restarting clears locked background services and temporary files.

Is Media Creation Tool better than direct ISO download?

Direct ISO downloads often complete more reliably because they bypass background service dependencies.

How much free space is required for ISO download?

Keep at least 30 GB free space for smooth verification and extraction.

Can slow internet cause the 99% freeze?

Yes. Network timeouts during final verification can freeze progress.

If new issues appear during installation after download, always validate the ISO checksum before creating a bootable USB or mounting the file.