Migrate from Windows 10 to Ubuntu – Previous: Preparation before installation

This article is suitable for scenarios where there is no U disk, want to completely cover the Windows system, single-install Ubuntu
This article contains Try twice: Failed to use EasyBCD for the first time, partition + EasyEFI for the second time
real stepping on the pit: Select the wrong hard disk, install Ubuntu to the F disk partition of the larger hard disk

1. Why write this

I plan to say goodbye to Windows completely and replace the main system with Ubuntu 26.04. I don’t have a U disk on hand, and I don’t want to buy it. I have searched a lot of tutorials on the Internet, and the mainstream method is to use easyBCD or rufus + U disk. But I found that easyBCD can’t boot the ISO at all in UEFI mode, and this path doesn’t work.

Eventually I took another approach:Draw a FAT32 partition on the hard disk, extract the Ubuntu installation file, and then use easyuefi to add a startup item. This method does not require any external device.

I recorded the whole process (including the failed attempt and the pit of the wrong hard disk), and attached 11 screenshots. As long as you follow the steps strictly, you can successfully complete the preparation before installation.

2. Preparations (list)

• A computer running Windows 10 (My model is ThinkPad T570)
• Ubuntu 26.04 LTS official ISO image:ubuntu-26.04-desktop-amd64.iso
• 10 GB free hard disk space (for temporary storage of installation files)
• administrator rights

⚠️ Important: Before operating, please all important data Back up to an external hard disk or cloud disk.

I have not made a backup. Because my idea at the time was that the data of the C drive does not need to be retained, and the data of the DEF disk is directly placed on the larger hard disk. As long as it is operated with caution, there will be no major problem.
Although I checked repeatedly, I still installed Ubuntu to the F disk (the smaller one) because of the misjudgment of the hard disk usage, resulting in the loss of all the data of the F disk.

Misjudged the usage of the hard disk: the computer has 2 hard disks, a smaller one is used for the F disk (Disk 0), and the larger one is used for the CDE disk (Disk 1).
Backup is the only reliable remorse medicine.

3. First attempt: easyBCD (failed)

3.1 Why try easyBCD first

Many tutorials on the Internet say that easyBCD can install Linux without a U disk, I decided to try this solution first.

3.2 Download and install

I downloaded the latest free version of EasyBCD and installed it on the C drive.

3.3 Failure Tips

Just opened EASHBCD, the result pops up an error window:

EasyBCD has detected that your machine is currently booting in EFI mode. Due to Limitations set by Microsoft, many of easyBCDS multi-booting features cannot be used in EFI mode and have been disabled.

After consulting the information, it is found that Microsoft has limited the function of Windows Boot Manager in UEFI mode, and EasyBCD cannot directly boot ISO images in EFI mode. This road doesn’t work.

3.4 Give up easyBCD

I decided to change it another way: instead of relying on the Windows Boot Manager, add a startup item directly at the UEFI level, pointing to a ‘fake U disk’ (Fat32 partition on the hard disk).

Fourth, the second attempt: hard disk partition + easyuefi (successful)

4.1 Core principles

10 GB of space is drawn on the D drive of the larger hard disk (Disk 1), formatted as FAT32(UEFI can recognize), and then copy all the files after Ubuntu 26.04 ISO extracted. Then use the easyuefi tool to add a startup item to the motherboard NVRAM, pointing to the grubx64.efi file. After restarting, the motherboard will start from this ‘virtual U disk’ and enter the Ubuntu installer.

4.2 Create a FAT32 partition

4.2.1 Open Disk Management

Press win + x, select disk management.

4.2.2 Compress 10 GB free space

I choose from D disk(10 GB of space is compressed for larger hard disks (Disk 1)). Because the D disk has enough remaining space.

Right-click the D-disk → Compress the volume → enter the amount of compression space:10240(Unit MB, i.e. 10 GB) → Click Compression.

After the compression is complete, a 10 GB block will appear in the disk management unallocated area, displayed as black stripes.

4.2.3 Configuration Items

• In the process of creating a simple volume wizard
• Assign drive letter: I chose g
• The file system must be selected FAT32

Click Finish and wait for the formatting to end. There will be a final disk management G drive(FAT32, capacity 9.99 GB).

4.3 Unzip Ubuntu 26.04 ISO to G drive

Do not use Rufus or floppy to write through, just need to simply decompress.

• Open with 7-Zip or WinRAR ubuntu-26.04-desktop-amd64.iso
• Select all files and folders to extract to G disk root directory

After the decompression is completed, the root directory of the G disk will appear boot,efi,casper,dists,pool other folders, and boot.catalog,md5sum.txt and other documents.

4.4 Download and install EasyEFI

EasyueFi is a UEFI startup item management tool with a free version (personal use).

• Search for ‘hasleo easyuefi’ to enter the official website, select hasleo easyuefi
• Download Free trial Version (enough to use this time)

It can be installed on the C drive during installation.

4.5 Create startup items with EasyEFI

4.5.1 Open EasyEFI

Start after the installation is complete, click the first button on the main interface ‘Manage EFI Startups’or ‘Windows Boot Manager’.

4.5.2 Create a new item

In the Start Items Management window, click ‘Create a new item’.

4.5.3 Fill in the parameters

• Types of: select ‘Linux or other operating systems’
• Description: fill in ubuntu installer
• target zone: Select the FAT32 partition you just created, namely G drive(Pay attention to the capacity and drive letter)
• file path: Click the ‘Browse’ button to navigate to G:\EFI\Boot\ directory, selected grubx64.efi File

If you don’t have it in your G drive efi\boot\grubx64.efi, you can try G:\efi\ubuntu\grubx64.efi Or G:\boot\grubx64.efi. In the decompression file of ubuntu 26.04,grubx64.efi Located \efi\boot\ down.

Click on ‘OK’ save.

4.5.4 Adjust the startup sequence

Find just created in the list of startup items ubuntu installer, through the right ‘Move up’ button moves it to first. After restarting, the computer will give priority to booting from this startup item.

5. Restart and enter the installer

After completing all the above steps, restart the computer. Press F12, if the startup sequence is set correctly, you will directly see the GRUB menu, and the options include ‘Try or Install Ubuntu’, ‘Ubuntu (Safe Graphics)’, etc.

Note: If the screen is black or Huaping at startup, press the ‘Try or Install Ubuntu’ option e key, find Quiet Splash, add later nomodeset, and then press f10 start up. This solves most graphics card compatibility issues.

After entering the Ubuntu desktop, click ‘Install Ubuntu 26.04 LTS”.

6. A big pit I stepped on: choose the wrong hard disk

In the ‘Installation type’ interface, I selected ‘Clear the entire disk and install Ubuntu’. The installer lists two hard drives:

• The first block: 238 GB (I thought it was a smaller hard drive, that is, the original C drive)
• The second block: 953 GB (I thought it was a larger hard disk, that is, the original def disk)

I chose 238 GB that piece. But after the installation is complete, go to ubuntu, I found The F drive on the larger hard disk (formerly 200 GB partition) becomes the Ubuntu system disk, all the data in it is lost. The original C drive (small hard disk) is still Windows, intact.

However, to be honest, although the F disk is overwritten by the Ubuntu system. The impact is also small. Because on Windows, my F drive is for virtual machines. The value of data retention is not great.

Why is this so? Because the hard disk order of the ThinkPad T570 is not displayed in C/D/E/F in the Ubuntu installer, but according to the Physical Interface Order. I mistakenly thought that the small capacity is the C drive, but in fact, the small capacity is an independent partition (F disk) on the larger hard disk, and the larger solid-state hard disk is 1TB (I only confirmed it later).

so,Don’t judge which is the Windows C drive by the size of the capacity. Correct practice:

• Before starting EasyueFi, in Windows Disk Management Write down the model and capacity of each hard drive.
• In the partition list of the Ubuntu installation interface, the hard disk model is also displayed (such as ‘Lenovo SSD 1TB’ or ‘WDC WD10JPCX…’).
• Select the hard drive you want to overwrite according to the model, not capacity.

7. Prepare to complete – next step

At this point, you have completed all pre-installation preparations:

• Create FAT32 partition and unzip Ubuntu 26.04 ISO
• Added the correct UEFI startup item with EasyueFi
• I know how to avoid the mistake of choosing the wrong hard disk

Select after restart ubuntu installer Start, enter the installation environment, and then Be sure to check the hard disk model carefully, select the hard disk you really want to override (usually the solid-state drive where the original Windows is located).

Regarding the official installation steps (partitions, user settings, boot repairs, etc.), I will explain in detail in the next article.

👉 Migrate from Windows 10 to Ubuntu – Next: Installation and System Configuration(coming soon)

Eight, reminder

1. Backup! Backup! Backup! I lost all the data of the F disk because of misjudgment of the hard disk.
2. Startup items added by EasyEFI are stored in the motherboard NVRAM, even if the hard disk is formatted. If you need to delete it after the installation is complete, you can go to EasyEFI to delete again.
3. If you want to go directly to Ubuntu after installation without the Windows Boot Manager, GRUB will take over automatically as long as you overwrite the hard disk where the Windows is located.
4. If you are still worried about choosing the wrong hard disk, you can temporarily disable the mechanical hard disk in the BIOS, and only keep the target hard disk. Enable after the installation is complete.

I hope this tutorial can help you avoid the pit I stepped on and move to Ubuntu 26.04 smoothly. If you have any questions, please leave a message.