[The Latest] 4 Effectively Fixes for Bootable USB Not Working on Windows PCs

If you're having problems like inaccessible boot device or error notifications, you may make a helpful move – create a bootable USB. This USB, loaded with Windows ISO files, is mainly for installing the OS and troubleshooting issues. You can use it to boot your PC and install Windows, whether your computer is working or not. It's also handy for fixing different PC errors by making the PC boot from the USB.

But sometimes, the bootable USB gives users trouble like the bootable USB not working, and they don't know why. In the next part, we will share the reasons with fixes, check them, and fix your Windows bootable USB.

Why is my bootable USB not working?

If you are wondering “Why is my bootable USB not working?” here are some possible reasons for reference:

● Unsupported USB Format

● USB is not showing up or recognized in BIOS

● Bootable USB is not detected as a boot device

● Incorrect boot order

● old USB drive like the 1.0 or 2.0 drive not supported by your Windows OS

● USB drive is damaged or corrupted

How to fix the bootable USB not working issue?

How can I boot from USB when the bootable USB is not working? You can try the following 4 effective methods to easily and quickly solve the problem. 

Fix 1. Check your USB drive
Fix 2. Convert the USB format to FAT32
Fix 3. Change the boot order
Fix 4. Recreate a bootable USB

You can choose the methods that suits your situation most.

Fix 1. Check your USB drive

If your USB bootable drive is damaged or not made correctly, your computer won't start from USB. Ensure your USB flash drive is prepared using the correct method and the proper creation tool. Windows can only boot from a USB drive if it's bootable. Therefore, confirm if your USB drive is genuinely bootable. You can choose reliable third-party software to check if you have successfully created a bootable USB. Alternatively, inspect the USB physically for any signs of damage.

Fix 2. Convert the USB format to FAT32

If the bootable USB has the wrong format, it might not work because the computer expects a specific format for proper booting. Most systems are compatible with FAT32, so if your USB is using NTFS by default or another file system, convert it to FAT32 to potentially fix Windows not booting from USB issue.

Step 1. On your keyboard, press the "Windows + R" at the same time to open "Run" Window, then type "Diskpart" and click "OK" (click Yes if prompted by the User Access Control).

Step 2. DISKPART will open in a command prompt window. And type the following commands in sequence:

Yet, this approach has limitations; it can't format a sizable drive (over 32GB) to FAT32. When attempting such formatting in Diskpart, you'll encounter an error stating "The volume size is too big for FAT32" like the following picture shows:

At this time, you can use AOMEI Partition Assistant, a multifunctional computer management toolkit that is designed for computer issue-solving. It doesn't face the 32GB limit for the FAT32 drive. In addition, it can handle tough formatting jobs like dealing with write-protected disks, RAW USB drives, and formatting internal hard drives to exFAT or Ext4/Ext3/Ext2. In the upcoming steps, we'll show you how to format a big USB drive to FAT32 to fix the issue of a non-functional bootable USB.

Step 1. Install and launch AOMEI Partition Assistant Professional. Right-click the large hard drive and select "Format Partition".

Step 2. Choose "FAT32" in the File System drop-down menu. You can also change cluster size, and partition label in this interface.

Step 3. Back to the main interface, click "Apply" to commit the pending operation.

Wait for seconds, the large hard drive will be formatted to be FAT32.

Note: If the current file system of the large hard drive happens to be NTFS, you can convert it to FAT32 without formatting via AOMEI Partition Assistant's "NTFS to FAT32 Converter". That feature allows you to convert file systems between NTFS and FAT32 directly without losing data.

Fix 3. Change the boot order

Another factor of bootable USB not working is when users connect the USB drive to the PC but overlook setting it up as a boot device. In such cases, Windows may fail to detect it. To address this, it's essential to configure the USB properly by setting it up as a boot device in order to ensure Windows recognizes it.

Step 1. Reboot your computer and press a key (e.g., F2, F11, ESC) on the initial screen to access BIOS. Look for "Boot Options" or a similar setting, and adjust the boot priority to favor the USB drive.

Step 2. Then save the configuration and exit the BIOS.

If the USB boot option isn't visible, your computer might not support this feature. In such cases, you may need to explore alternative methods.

Fix 4. Recreate a bootable USB

If the previous methods haven't worked and your USB is physically fine, it is a good idea to consider recreating a bootable USB using AOMEI Partition Assistant. Once created successfully, you can use it to address the issues on your PC that you initially wanted to fix. For example, if you're meeting boot problems, the Rebuild MBR function can be employed to fix the corrupted MBR without requiring an installation disk.

If you successfully fix the problem that it can't boot from USB, it is also advisable to recreate one as a emergency use in case of accidents.

★Before we get started, you need to prepare:

A functional computer.

Install AOMEI Partition Assistant Professional on this computer.

An empty USB drive or CD/DVD.

Backup any data on the USB media that you need, as it will be formatted.

Step 1. Connect the USB to a working Windows PC and run the installed AOMEI Partition Assistant Professional. On the main interface, click "Make Bootable Media" under the "Tools" menu. Click "Next".

Step 2. Select "Burn to CD/DVD" or "USB Boot Device" according to the media you inserted. Then click "Proceed".

Step 3. There is a message that your USB drive will be formatted. Back up the information you need, and click "Yes" to continue.

Creating a WinPE bootable USB drive takes a few minutes. Then, you'll have a full partition manager on the USB or CD/DVD. Connect it to another Windows PC to use it. To boot from the USB or CD/DVD, change the boot order in BIOS under Boot Menu.

Step 1. Turn on the PC and press the BIOS key. The BIOS key varies by manufacturer; you can find it in the instruction book or by searching on Google.

Step 2. Enter BIOS setup, and select the "boot" tab with arrow keys. And choose "change boot order".

Step 3. Set the bootable manager on the first order in the listed devices. Then save the change.

And you will see the AOMEI Partition Assistant, and repair or manage your hard drive with its Rebuild MBR feature.

Summary

The 4 fixes can be effective for fixing bootable USB not working. With AOMEI Partition Assistant, you can also easily solve many other computer problems. You can use it to easily extend drive space, convert between MBR and GPT, clone disk, migrate OS, and so on. If you are a Windows Server user who want to effectively manage your computer, the software offers the Server edition.