Troubleshooting Guide

Issue 1: Windows Defender/Antivirus Blocking

Tools that modify system files to bypass Microsoft’s hardware checks are flagged as Potentially Unwanted Applications or dangerous by Windows Defender or any other antivirus program.

Solution 1: Allow the Tool When Blocked (Easiest)

1. When Windows Defender blocks the tool, you will see a threat found message.
2. Click on the message and open Windows Security.

3. Go to Protection History.

4. Find the blocked item, it’ll be something like: HackTool:Win32/…” or “PUA:Win32/…
5. Click on it and see more details.

6. Click Action and choose Allow on all devices.
7. The file will come back and won’t be blocked again.

Solution 2: Turn Off PUA Protection For Now

1. Open Windows Security

2. Click on Apps & Browser Control

3. Click Reputation based protection settings
4. Scroll down to get Potentially Unwanted App blocking

5. Turn off these switches: Block Apps, Block Downloads

6. Now run Flyby11

Solution 3: Tell Windows To Ignore A Specific Folder

1. Open Windows Security and click Virus and Threat Protection
2. Go to Virus and Threat Protection settings and then Manage settings
3. Scroll down and click add or remove exclusions

4. To Add an Exclusion, add the Flyby11 folder
5. Windows Defender will now ignore everything from that folder

Solution 4: Turn off Real-time Protection Temporarily

1. Go to Windows Security, then Virus and Threat Protection
2. Click Virus & threat protection settings and then Manage settings
3. Turn off Real-time protection

Issue 2: Keep Files Option Is Greyed Out

The option to keep your files, settings, and apps can be blocked if your current Windows 10 and Windows 11 downloads don’t match in language or edition, or if your Windows 10 version is too old.

Solution 1: Make Sure Downloads Match Your Current Windows Exactly

Step 1: Find Out What Windows You Have Now

• Press Windows key + I to open settings
• Go to Time & Language and Language & Region
• Write your Windows display language like English: United States or English: United Kingdom

• Also, write your Country or Region in settings
• Press Windows key + R and type winver, then press Enter

• Write down your Windows edition (Home, Education, Pro, etc) and version like (22H2)

Step 2: Download Matching Windows 11

Using FlyOOBE/Fido Script:

• Run the ISO download feature
• Select the same language that matches your system

• Choose the same Home/Pro as your current Windows 10
• Let it download from Microsoft servers

Manual Download from Microsoft

• Go to Microsoft official page

• Now go to Download Windows 11 Disk Image ISO
• Select your exact language from the drop down menu
• Download the ISO file

• You can also use Rufus o Fido

Better & More Reliable Method

• Go to Rufus and click the download button in Rufus to download the ISO file directly.

• Open the Microsoft page from a Mac, Linux computer or phone to see direct download options.
• Use Windows ISO downloader or Fido PowerShell script for direct download.

Step 3: Make Sure Everything Matches Perfectly

• The ISO edition should match your current Windows edition exactly
• The language should match
• And for best results, update your Windows 10 completely to the latest version 22H2.


Solution 2: Use DISM To Fix System Files

• You see the option still greyed out even after the language and edition matches, what you can do is:
• Right click the Start button and choose Command Prompt (Admin) or Windows PowerShell Admin

• Type these commands one after another and press Enter after each:
  • DISM /Online /Cleanup-Image /CheckHealth
  • DISM /Online /Cleanup-Image /ScanHealth
  • DISM /Online /Cleanup-Image /RestoreHealth
• Wait for each command to finish which can take 15-30 minutes.

• Then type this command: sfc /scannow

• Restart and try upgrading again


Solution 3: Free Up Disk Space

There’s a chance that the option can be greyed out because you don’t have enough space.

• Open settings then go to System and then Storage.

• You need at least 64GB of free space while 80+ GB is recommended.

• Use Storage Sense to clean up old files

• Delete the old Windows.old folder if there is
  • Run Disk Cleanup as administrator
  • Check the Previous Windows Installation box
  • Also delete temp files and downloads
  

Issue 3: Installation Fails With Errors Or Freezes

Error code 0xC1900101-0x3000D means a driver problem happened during the first restart. Common issues can be incompatible drivers, internet connection problems, or hardware conflict.

Things To Do Before Upgrading

Step 1: Disconnect from the Internet

Why because it stops Windows from downloading incompatible drivers during update.

Step 2: Unplug Unnecessary Hardware

Only keep keyboard, mouse, and if you’re using a USB drive with Windows 11. Unplug all external hard drives, printers, USB hubs, webcams, card readers, gaming controllers or other gaming devices.

Step 3: Update Important Drivers

Graphics Drivers:

• Visit the graphics card maker’s website:
  • NVIDIA cards: nvidia.com/drivers
  
  • AMD cards: amd.com/support
  
  • Intel graphics: intel.com/content/www/us/en/download-center
  
• Download the latest Windows 10 drivers or Windows 11 if they have it.
• Install and restart your computer.

Storage/Chipset Drivers:

• Visit your computer manufacturing website, like Dell, HP, Lenovo, etc.
• Go to the support page of your exact same model.
• Download the latest chipset and SATA/NVMe drivers.
• Install and restart your computer.

Step 4: Uninstall Third-Party Antivirus Software

After uninstalling your antivirus, download and run the special removal tool from the antivirus company:

• Norton Removal Tool

• McAfee Consumer Product Removal Tool

• Avast Uninstall Utility

Now restart your computer.

Step 5: Do A Clean Boot

• Click Windows + R, type msconfig, and press Enter.

• Now go to the Services tab

• Check the box that says Hide all Microsoft services
• Select Disable All

• Go to the Startup tab and click Open Task Manager
• In that, disable all startup items and restart your computer

Step 6: Check BIOS Settings (Important for Bypass Tools)

• Restart your computer and press the BIOS key during startup, which is usually Del, F2 or F10.
• Some bypass tools might need Secure Boot to be disabled, and the TPM to be disabled.
• Save the changes and exit.

You can also run the Windows update troubleshooter. Let it find the issue and fix it, and make sure all the pending Windows updates are installed before you upgrade.

During The Installation

• Start the bypass tool with your internet still disconnected.
• If the installation freezes at the first restart (SAFE_OS phase)
  • Wait at least 2 hours before doing anything.
  • If it’s truly stuck, hold the power button to force your computer to shut down
  • Restart and it’ll go back to Windows 10
  • Try the upgrade again and try the cleanups we mentioned above.

If It Still Doesn’t Work

Check Event Viewer for Specific Error Details

• Press Windows key + X and choose Event Viewer.

• Go to Windows Log and Setup
• Look for errors with code 0xC1900101 and the part where the dash tells you which phase failed
• Search online for the specific error code and get solutions.

Issue 4: Can’t Download Or Mount The ISO File

Microsoft download tools can fail because of server timeouts, corrupted downloads, not enough temporary disk space, or your internet provider or firewall blocking Microsoft download servers.

Solution 1: Download Manually From Microsoft

Step 1: Go to the Official ISO Download Page

1. Now go to the Microsoft Page to Download it
2. If you’re on a Windows computer, it might try and make you use the Media Creation Tool instead.
3. Get around this and get the direct download access:
   • Open the page from a Mac, Linux computer or a mobile.
   • You’ll see the direct download option.
4. You can also use Rufus o Fido

Step 2: Download the ISO

• Select Windows 11 (multi-edition ISO) and click download.
• Choose your language and click the 64-bit Download button.

• Save it to a place with at least 6 GB of space.
• Wait for the download to finish (it’s a 5-6 GB file).

Step 3: Make Sure the ISO Downloaded Correctly

• Right-click the ISO file and choose Properties.
• Check the file size (should be around 5.1-5.7 GB).

• If it’s smaller, the download is corrupted, so download it again.
  • Optional: Check the SHA256 hash against Microsoft’s published values for extra security.

Solution 2: Use Third-Party Download Tools

Rufus:

• Download Rufus
• Open Rufus, but you don’t need to install it.
• Click the download option (it’s a down arrow next to the SELECT button).
• Choose Windows 11 and select the version, edition and language you want.

• Save the ISO to your computer.
• You can use this ISO file without needing to create a USB drive.

Fido PowerShell Script:

• Download the Fido Script from GitHub (Search for “pbatard Fido”)

• Right click and choose Run with PowerShell.
• Select Windows 11 edition and language.
• The script downloads directly from Microsoft servers.
• It shows download progress and automatically checks if the file is correct.

Solution 3: Fix Problems With Mounting The ISO

If double-clicking the ISO doesn’t work:

• Check the file extension to make sure it ends with .iso and not .iso.tmp or .partial.
• Rename the file and remove any special characters, and keep it simple like Win11.iso.

Mount it Manually:

• Right-click the ISO file.
• Select Mount from the menu.
• The ISO will appear as a new drive under This PC in File Explorer.

If the mount option isn’t available, use PowerShell:

• Right click Start and choose Windows PowerShell (Admin).

• Type: Mount-DiskImage -ImagePath “C:\path\to\your\file.iso” (Replace the path with where your ISO file actually is)

If Mounting Fails:

• Open Command Prompt as Administrator.
• Type: diskpart and press Enter
• Type: list volume and press Enter (write down any volumes using letters D through Z)
• Type: exit and press Enter

Use 7-Zip to Extract Instead:

• Download 7-Zip
• Right click the ISO file

• Choose 7-Zip, then Extract to Win11.
• Point Flyby11 to the extracted folder, and it’ll work even if mounting failed.