By Jessie / Last update October 21, 2022

Why Windows 11 Install Stuck at 99?

There are many reasons why Windows 11 install stuck at 99%, and understanding the reasons will help us to solve the problem better. Next, this article lists a few of the most common causes.

  • Unstable Internet connection: This is the cause of most Windows installations getting stuck, and network reasons may also cause the downloaded files to be corrupted.
  • Unstable power supply: Windows 11 updates are installed at startup. If the power supply is unstable, it may interrupt the installation process and cause the Windows 11 update stuck.
  • Insufficient storage space: One of the causes of Windows 11 taking forever to install may be insufficient storage on the system drive. Therefore, make sure that you clear enough storage space to complete the process before starting the installation.
  • Corrupt ISO file: The ISO file is the most important in the Windows 11 installation process and if it gets corrupted, the installation process will face certain obstacles.

How to Fix Windows 11 Install Stuck at 99

Windows Update takes a long time to download and install the updated components and files to your device. If Windows 11 Installation Assistant is stuck at 99% or 0% within 4 hours, this is normal. The reason why installing Windows 11 might seem to take so long can be related to slow hardware components in your device. The system drive on which you're installing Windows 11 is especially important: SSD or HDD.

However, if it takes longer than that, there might be something wrong with this update process. You need to take some measures to fix this problem. Next, this article will introduce 3 simple methods in turn, you can try these methods one by one to help you. And you can also learn a method to backup your system regularly to protect data from any damage.

Fix 1. Run Windows Update Troubleshooter

Microsoft offers several built-in troubleshooters to automatically diagnose and fix issues with the system. It’s recommended that you run a relevant troubleshooter whenever a problem is encountered.

Step 1. Press Windows + I to launch the Settings app, and click on Update & Security.

Step 2. Select the Troubleshoot tab from the navigation pane on the left.

Step 3. Click on Additional troubleshooters.

Step 4. Next, click on the Windows Update entry.

Step 5. Finally, click on the Run the troubleshooter button to identify and fix issues with Windows Update.

Run Troubleshooter

Step 6. Choose the appropriate response and follow the on-screen instructions to complete the troubleshooting process.

Fix 2. Pause the Update and Try Again Later

Step 1. Press Windows + I to launch the Settings app, and then click on Update & Security from the options listed here.

Step 2. Next, click on Pause updates for 7 days on the right.

Step 3. Restart the computer, again navigate to the Update & Security settings, and click on Resume updates.

Step 4. Once done, click on Check for updates, and see if the Windows 11 install now progresses and is not stuck.

Check For Updates

Fix 3. Uninstall Conflicting Drivers

There are a bunch of devices that are known to conflict with the upgrade process and could lead to the Windows 11 install stuck at 99% problem. So, you need to uninstall conflicting drivers.

Step 1. Press Windows + R to launch the Run window, enter devmgmt.msc in the text field, and click on OK to launch the Device Manager.

Step 2. Now, locate the problematic category and double-click on it to view the devices under it.

Step 3. Right-click on the device that’s responsible for the Windows 11 upgrade being stuck, and select Uninstall device from the context menu.

Step 4. Tick the checkbox for Delete the driver software for this device and click Uninstall.

Uninstall Conflicting Driver

Clone the Disk to a Larger One

As mentioned earlier, if the storage space is insufficient it can also cause Windows 11 installation to get stuck at 99%. Therefore, it is recommended that you check if you have enough space on your disk before installing Windows 11.

If you don't have enough space and don't want to delete something to free up disk space, then you can choose a reliable free disk cloning software to help you, such as AOMEI Backupper Standard, which can help you clone your current disk to a larger one to get more space for storing Windows 11.

Disk Clone

Backup Your System Regularly to Protect Your Data from Any Damage

Windows 11 install stuck at 99% may cause some data loss. To avoid this error from happening again or any errors that may pose a risk of data loss, it is recommended that you backup your system regularly. The free backup software AOMEI Backupper Standard can help you easily achieve the goal.

  • Schedule backup: You can set different frequencies (Daily, Weekly, Monthly) to backup your system regularly. And the software will automatically backup the system according to the frequency you set.
  • Incremental backup: When you perform scheduled backup, you can use incremental backup method for the backup task which will only backup the changed parts, thus this method will help you to save backup time and storage space.
  • Multiple backup paths: You can backup your system to multiple destination locations, such as HDD, SSD, USB drive, cloud, network, etc.
  • Different OS: This freeware supports many different Windows operating systems, such as Windows 7/8/8.1/10/11/XP/Vista, etc. If you are a Windows Server user, AOMEI Backupper Server will more suitable for you.

Step 1. Download AOMEI Backupper Standard, install and launch the software. You can click Backup > System Backup.

Download FreewareWin 11/10/8.1/8/7/XP
Secure Download

System Backup

Step 2. You can modify the Task Name to distinguish it from other backup tasks. The software will select the system and boot partitions by default as the source. Please select a destination path for your system. 

Select Destination

Notes:

  • Schedule Backup: You can set the fixed intervals to run the system backup task automatically such as daily, weekly, monthly event trigger or USB plug in. The last two are available in the Pro version.
  • Backup Scheme: You can choose different backup methods, both incremental and differential backup can help you improve backup efficiency, but incremental backup is more demanding for restoration. You can upgrade now to the professional version (5% off for one computer) to enjoy differential backup method. After upgrading, you can also enable automatic backup cleanup feature.

Step 3. Confirm all your operations and click Start Backup to perform the system backup.        

Start Backup

Summary

This article talks about the causes of Windows 11 install stuck at 99%, when you encounter this problem, you can try 3 solutions mentioned in this article to help you. To avoid data loss caused by similar errors, we recommend you to backup your system regularly with the free and safe backup software AOMEI Backupper Standard. It can automatically backup your system for you according to the backup frequency you set. You can also use incremental backup to improve backup efficiency and save disk space.

Besides, it is also a professional restore software. When you encounter a problem that makes your system unusable, you can use your system backup image to restore it. Even if you want to restore your system backup to a computer with different hardware, its Universal Restore feature can do it easily. You can download this software to discover more useful features.