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8 Solutions to Non System Disk or Disk Error in Windows 10/8/7

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When booting up the computer, some Dell users encounter the following error which reads "Non-system disk or disk error replace and strike any key when ready". See the following image:

non system disk or disk error

Reasons behind this error message vary. According to Microsoft, this issue may occur if your start device (such as a floppy disk drive, hard disk drive, or CD-ROM drive) does not contain boot files. But users also report more possible reasons. In this post, we tell how to fix non system disk error by 8 solutions.

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Fix 1. Remove All Non-system Disks

Similar to "Boot Device Not Found" issue, the first trying is to remove the non-system disk from your boot device because the boot order can be changed for some reasons. For example, you can remove any non-system disk from the floppy drive or eject the disk from the CD-ROM drive. Then turn off and turn on the computer to have a check.

Fix 2. Confirm the Boot Sequence

You can also enter BIOS to confirm whether the disk containing boot files is set to the first place of the boot order. If not, you will need to change your computer's boot sequence. To do this, you must change your computer's setup and the option that controls which device your computer uses to start from. Make sure that you select a device that has boot files (or operating system files) installed.

Fix 3. Remove and Reinstall the Hard Drive

If the computer was dropped or jarred, there may be a bad connection between the hard drive and computer. You might have to remove and reinstall the hard drive. Here is how to fix non system disk error by using this way:

Step 1. Cut off the power.
Step 2. Remove the battery if it is a laptop.
Step 3. Remove the system disk.
Step 4. Reinstall the system disk.
Step 5. Reinstall the battery if it is a laptop.
Step 6. Power on the computer.

Tip: if there is a different machine available, connect this drive to that computer to confirm whether the problem arises from the hard drive or the computer.

Fix 4. Perform Startup Repair

Startup Repair helps fix non system disk or disk error in most cases. First of all, disconnect any external devices connected to the computer. Then inject Windows installation disc. Finally, follow the below-mentioned steps to troubleshoot the issue:

Step 1. Enter BIOS and set PC to boot from the installation disc.

Step 2. Wait for Windows to load files. When you see the Windows Setup interface (for Windows 10, it is "Windows Setup"; for Windows 7, it's "Install Windows"), select the language, time and currency format, keyboard or input method and click Next.

windows setup

Step 3. Click the Repair Your Computer link.

repair your computer

Step 4. For Windows 10 users, select Troubleshoot –> Advanced options –> Start-up Repair –> Choose a target operating system and then Windows will start diagnosing your system. If a problem is found, Windows will try to fix the problem automatically or suggest a solution. Just follow the prompt to fix the "Non system disk or disk error" issue.

win10 startup repair

For Windows 7 users, wait for the System Recovery Option to load your operating system. When your operating system is listed in the box, just select it and click Next to fix problems when starting Windows. You will be asked to choose a recovery tool. Here choose the first one named Startup Repair. Please wait patiently while this tool is searching for problems and trying to resolve the issue.

win7 startup repair

Step 5. After doing these, click Finish to restart your computer.

But if no problem is found, you can go for the rest solutions with the help of MiniTool Partition Wizard Bootable CD.

Tip: To get MiniTool Partition Wizard Bootable CD, you should first of all get MiniTool Partition Wizard Pro and then make use of its Bootable Media feature to create a bootable media. The following two articles will help you create and boot computer from a MiniTool Bootable Media.

Fix 5. Repair MBR

Virus infection and hard drive failure often lead to MBR (master boot record) damage. Many viruses target the MBR, the most important part of your hard drive. And, if the area where the MBR is located contains a few defective clusters, the MBR is rendered unreadable, bringing the "non-system disk or disk error replace and press any key when ready" message. Luckily, MiniTool Partition Wizard is able to create a brand new master boot record, allowing your computer to now boot normally.

Step 1. At the main interface of MiniTool Partition Wizard Bootable CD, select the system disk and choose Rebuild MBR from the action panel.

Step 2. Click Apply at the top left corner to confirm this operation.

rebuild mbr

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However, if the "Non system disk or disk error" error message insists, repairing the HDD's boot sector, master boot record and BCD (Boot Configuration Data) altogether. To do so, you need the help of Windows installation disc.

Step 1. Insert a Windows installation disc into the affected computer and set it as the first boot device in your computer's boot order.

Step 2. When you see the Windows Setup window, press Shift+F10 at the same time to call out the command Prompt window.

Step 3. Type the following commands into the Command Prompt and press Enter key after typing in each one:
bootrec /fixmbr
bootrec /fixboot
bootrec /rebuildbcd

rebuild mbr cmd

Then you can remove the installation disc, restart the computer and see if the non system disk or disk error has been resolved.

Fix 6. Set System Partition Active

Several HP users also report their issue is successfully fixed by setting the system partition active. As we know, virus attack can get the system configure wrong, leading to the system partition inactive and further causing the non system disk or disk error.

MiniTool Partition Wizard Bootable CD can help you check whether the system partition is set as inactive partition and reset it active if things get messed up.

Boot your computer to the main interface of MiniTool Partition Wizard Bootable CD and then view the status of all partitions on the boot disk. If you see no partition is set active or a wrong partition is set as active partition, just select the system partition and then choose Set Active from the action panel. Finally, click Apply button on the tool bar.

set active

Note: Always mark the System Reserved Partition (generally 100mb) active. If you don't have a System Reserved Partition then mark C: Drive (C drive may have a different drive letter in Windows PE) as the active partition.

Tip: you can also do this job in the command prompt of Windows installation disk. Please set your computer to boot from the installation disc. Then press Shift + F10 at the same time to load the command prompt. Now, type these commands in order:

  • Diskpart
  • List disk
  • Select disk 0 (System drive is always configured as disk 0. However, enter the correct number in your own case.)
  • List partition
  • Select partition 1 (System partition is always configured as partition 1. However, enter the correct number in your own case.)
  • Active
  • Exit

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Fix 7. Check Bad Sector

Many computer startup issues are caused by minor errors like bad sectors on the hard drive. The hard drive test will detect these errors for you to have a reference. Please make sure there is a good physical connection between the hard drive and the computer. Then you can enter the main interface of MiniTool Partition Wizard Bootable CD.

Step 1. Select the boot device and choose Surface Test from the action panel.

surface test

Step 2. In the pop-up window, click Start Now to begin the test. Note that if any error is found, the corresponding small block will be marked with red. If there are some bad sectors found, you should go ahead and follow Fix 8.

start now

Fix 8. Replace Hard Drive and Reinstall OS

If there are a lot of bad sectors found on the drive, it looks your hard disk has crashed. We would recommend you back up all data immediately before it is too late. Then you may head to the repair center to shield the bad sectors and then reinstall Windows OR you may just replace the hard drive after the backup. (If you have the latest backup available, you can simply skip this part.)

Tip: before you back up the hard drive, it is necessary for you to check and fix the file system errors so as to copy the hard drive smoothly. Luckily, you can use MiniTool Partition Wizard Bootable CD to complete both tasks.

How to Check and Fix File System

Step 1. Select a partition on the system disk and choose Check File System from the action panel.

check file system

Step 2. In the pop-up window, choose "Check & fix detected errors" and then press Start button.

check fix errors

Repeat these steps on the rest partitions. When MiniTool Partition Wizard has finished checking and fixing all partitions on the boot drive, it is time for you to copy all data on it to make a backup in case that this drive may fail soon.

How to Back up the Boot Drive

Step 1. Choose Copy Disk from the tool bar.

copy disk

Step 2. Skip the welcome page by clicking Next.

welcome

Step 3. Select the system disk as the drive you want to copy and then click Next.

select disk to copy

Step 4. Select a hard drive as the target disk. Note that the target disk should be a basic disk, and all data on it will be removed. Hence, please make sure the selected target disk can be cleaned or back up the important data first if there is any. Then click Next to go on.

select target disk

Step 5. In the next interface, you can preview the default disk layout of your target disk. Or you can choose other copy options and then drag the slider bar to adjust each partition size. Click Next to continue.

  • Fit partitions to entire disk will automatically adjust each partition size to occupy the whole disk space.
  • Copy partition without resize will copy all partitions there with their original partition size. This requires that the target disk is not smaller than source disk.
  • Align partitions to 1 MB will improve the disk performance if the selected target disk is an SSD or advanced format disk.
  • Use GUID Partition Table will turn the target disk to a GPT disk.

how to boot from target disk

Step 6. Here you will be told how to boot from the target disk. Since the original operating system is unbootable, you can ignore this message and click Finish.

view changes

Step 7. Finally, click Apply button to start the copy.

apply

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Kindly reminds: Above solutions are all based on the condition that the system disk is successfully recognized in BIOS. If the system disk cannot be recognized even by the Windows installation media and no backup is available, you need to give the disk to a data recovery service which is likely to be an expensive option. In addition, to get a normal running OS, you will need to buy another hard drive and install Windows operating system on it.

Summary

So the bottom line here is that when your computer reports "non system disk or disk error", you can try the above methods one by one to take your chance. We hope you will never take the last one. If you have any further questions or suggestions, type your idea in the following comment section. Or you can contact our support via [email protected]. Thanks in advance!