Easy Solutions for Fixing the error BOOTMGR is Compressed

I. Why does the prompt BOOTMGR is compressed appear?

The full name of BOOTMGR is Windows Boot Manager. It is an important bootloader file that helps the Windows operating system start and can execute winload.exe to load necessary device drivers. BOOTMGR files are usually read-only and located in the boot directory of the “active” partition. If compressed, the system will not start.

The “BOOTMGR is compressed” prompt may appear due to software claiming to improve performance or optimize the system being installed, compressing the entire system disk, including BOOTMGR files. Additionally, it could be caused by mistakenly checking the “Compress this drive to save disk space” option in the system disk properties.

Now that we understand the cause of the “BOOTMGR is compressed” error, let’s move on to the solution to the problem.

II. How to solve the prompt BOOTMGR is compressed when booting?

1. Use the startup repair function

The Startup Repair feature resides in the Windows Recovery Environment and can fix many startup problems. Specific steps are as follows:

Step 1: Insert the Windows 10 installation disk and set the first boot sequence to the disk in BIOS settings. Restart the computer and select “Repair Your Computer” on the Windows Installer screen to enter the recovery environment.

Step 2: Enter the recovery environment, choose (Troubleshooting)>(Advanced Options)>(Startup Repair), wait for Windows Startup Repair to finish, then restart the computer to check if the issue is fixed.

2. Uncheck (Compress this drive)

Accidentally checking the “compress this drive to save disk space” option in the properties of the system disk (C:) can cause Windows to fail to boot with an error of “BOOTMGR is compressed“. To resolve this, try entering safe mode and unchecking this option in the future.

Step 1: Insert the Windows 10 installation disk and set the first boot sequence to the disk in BIOS settings. Restart the computer and select “Repair Your Computer” on the Windows Installer screen to enter the recovery environment.

Step 2: After entering the recovery environment, select (Troubleshooting)>(Advanced Options)>(Startup Settings).

Step 3: Click the (Restart) button in the lower right corner to restart the computer.

Step 4: When the computer restarts, press the corresponding number (such as F4/F5/F6) in the startup setting menu to select the safe mode you need to start. For example, press (F4) to enable safe mode.

Step 5: In safe mode, right-click system disk (C:) in file explorer, select (Properties), uncheck (Compress this drive to save disk space) in (General) tab, click (OK). Remove Windows installation disk, restart computer to check problem resolution.

3. Decompress BOOTMGR through the Compact command

If you cannot enter safe mode, you can also decompress BOOTMGR through the Compact command. Specific steps are as follows:

Step 1: Insert the Windows 10 installation disk and set the first boot sequence to the disk in BIOS settings. Restart the computer and select “Repair Your Computer” on the Windows Installer screen to enter the recovery environment.

Step 2: After entering the recovery environment, select (Troubleshooting)>(Advanced Options)>(Command Prompt).

Step 3: Enter (compact /u C:\bootmgr) in the command prompt window, press Enter, delete compression attribute from directory C:\bootmgr. Remove Windows installation disk, restart computer to check if problem is resolved. For more info on Compact command, refer to Microsoft’s official instructions.

4. Manually update BOOTMGR

We can also try to manually update BOOTMGR to solve this problem, the specific steps are as follows:

Step 1: Insert the Windows 10 installation disk (DVD or USB flash drive) into the computer. Continuously click F2 or F10 or DEL or ESC shortcut key (varies with the computer brand) to enter the BIOS setting interface when starting up, set the first boot sequence to the Windows installation disk, then save the settings, restart the computer, and make the computer start from the installation disk, Select the (Repair Your Computer) option on the Windows Installer “Install Now” screen to enter the recovery environment.

Step 2: After entering the recovery environment, select (Troubleshooting)>(Advanced Options)>(Command Prompt).

Step 3: In the opened command prompt window, enter (bcdboot d:\windows /s c:) (copy the BCD file in the d:\windows folder to the system boot partition c:), and press the (Enter) key . Then shut down and remove the Windows installation disk, and then restart the computer to see if the problem is resolved. For more information about the BCDBoot command, check out the official instructions written by Microsoft.

● (d:\windows) in the command refers to the location of the root directory of the Windows system. Please enter the corresponding drive letter and directory according to the disk location where your Windows installation is located.

● The (c:) in the command refers to the boot partition, please fill in the correct drive letter according to the actual situation.

The above is the solution to the prompt “BOOTMGR is compressed” when booting up. When the system cannot be accessed normally, in order to avoid data loss in the computer, you can view the content of the third part, the method of transferring or restoring data without entering Windows.

III. When Windows fails to start, use Renee PassNow to transfer or recover data

1. What is Renee PassNow?

Renee PassNow is a professional system rescue software for Windows users. It can clear Windows account passwords, create new administrator accounts, restore disk/memory card data, recover data after hard disk formatting, transfer disk files, erase or scan disk files, and repair various Windows system problems. Compatible with Windows 10/8.1/8/7/XP/Vista.

2. How to use Renee PassNow to transfer or recover data?

When Windows fails to start, create a startup disk with Renee PassNow to access files by booting the computer from the disk.

Step 1: Download and install Renee PassNow on a functioning computer, connect the U disk, select “Create a rescue USB disk” option, and follow the on-screen instructions. Remember to back up important files from the U disk before proceeding as all data will be deleted.

Step 2: Select (x64) or (x86) based on the system type, download the ISO file by clicking (Download Now), create a Rescue USB by clicking (Create Rescue USB) after the download is complete, and eject the USB by clicking (Eject USB).

Step 3: Connect the boot device to the computer, enter BIOS by pressing the shortcut key displayed on the screen, set the boot U disk as first in Boot Priority, save settings, and restart the computer.

Step 4: Wait for a while, after Renee PassNow is loaded, select (Data Transfer).

Note: If you need to transfer or backup the data of the entire hard disk, you can select the (data backup) option. If you need to run the command prompt as an administrator, but the account you log in is not an administrator, you can create a new administrator account through the (PassNow)>(Create New User) function of Renee PassNow.

Step 5: You can click on each disk drive letter (C/D/E/F, etc.) to check whether important files are lost. If not, it is recommended that you transfer them to an external disk. The operation of transferring data is very simple. For example, if you want to transfer the data in the C drive to the G drive, you can first select the C drive on the upper left, select the G drive on the upper right, and then select the files in the C drive, and click the Copy function button in the middle. Disk data can be easily transferred. If there is a file you want to delete, you can also click the (Delete) button in the middle after selecting the file, but the deletion operation cannot be undone, please operate with caution.

Step 6: If you find that there is data loss, please select the (Undeleter) option on the main interface of the function, and click the (Run) button.

Step 7: Select (Partition Recovery) to scan the target hard disk.

Step 8: After the scan is complete, select the file to be recovered, click the (Recover) button to execute the data recovery command, please save the file in another external disk, eject the U disk after the recovery is complete, and then perform other repair operations on the computer