Windows 10 Startup & Boot problems - Advanced Troubleshooting

Are you an IT admin and need to troubleshoot Windows boot problems? If the answer is yes, then in this guide, we will share advanced troubleshooting for Windows 10 startup and boot problems. Before you begin, we recommend you check out our following post:

• Windows 10 PC will not boot up or start

If the basic troubleshooting there does not help you, read on!

Windows 10 Startup & Boot problems

Boot Phases of a Windows 10 computer

When you push the power button, the boot process goes through many phases. Before we go ahead and troubleshoot the problems which occur during the stages, lets first get to know about them, and what happens during the process.

1]  PreBoot

When you hit the power button, the computer firmware starts POST or Power-On Self test and loads firmware settings. It checks if there is a valid disk system to start the next phase. It's indicated by an MBR or master boot record. The PreBoot process then starts the Windows Boot Manager.

2] Windows Boot Manager

The job of Windows Boot Manager is simple. It loads another program -Windows Loader, popularly known as Winload.exe. Its located on the Windows Boot partition.

While it may seem to be a redundant process, the primary reason it exists to help you boot into the right OS. When you have multiple OS installed on the same computer, it makes sure to load the right Winload.exe.

3] Windows OS Loader

Windows OS Loader now loads essential drivers to start the Windows kernel. The Kerner finally does the rest of the thing to give you an OS where you can work.

4] Windows NT OS Kernel

In the last stage, kernel picks up system Registry hive, and additional drivers mark in the BOOT_START list. Then the control is passed on to the session manager process (Smss.exe). System Manager in-turn initialize the system session and loads up rest of the hardware and software needed.

Advanced troubleshooting for Windows boot problems

If you are still wondering why so many phases, then my best guess that it's intentional. Imagine if it were just one program, it would have been almost impossible to figure out where exactly the problem occurred. Lets finally start with the troubleshooting.

1] The Computer repeatedly boots to the recovery mode

When you turn on the computer, and it boots into recovery option every time, we will have to use the Bcdedit program to break the loop.

• Click on Troubleshooting > Command Prompt
• Type Bcdedit /set default recoveryenabled no and hit Enter.

If the F8 options (Windows Safe Mode) don't work, set the Safe Mode to work in legacy mode. Use the following command Bcdedit /set default bootmenupolicy legacy

2] Windows stuck with a blank monitor with no activity

BIOS phase is where the system goes from PreBoot to Loading Windows OS. Its only marked as complete when there is no hardware issue in the system. So to check if it is a hardware issue:

• Remove external hardware and boot again.
• Check if your hard drive is working. If its too silent or there is no blinking LED, it's probably dead.
• If you cannot check that, press the Num Lock or Caps Lock to check if the indicator light toggles on and off.

3] Windows stuck at a blank monitor with a blinking cursor or an error message

When you get to see just a blink of an error message, then there is a problem with the Boot loader phase. The error message can include corruption of BCD/MBR boot sector/Bootmgr or missing OS or not able to boot due to system hive missing or corrupted.

Startup Repair tool

This tool is available under Advanced Options of Windows Recovery option. It can diagnose the logs, and fix complex startup problems automatically which does not let the computer boot properly.

1. Create an installation media of the same version of OS installed on the computer.
2. When you reach Install Windows screen, click on Repair your computer link.
3. Shutdown after the repair is complete.
4. Next, turn on your PC to see if Windows can boot properly.

To analyze further, you can take a look at the log generated by the Startup Repair tool. It is located at %windir%\System32\LogFiles\Srt\Srttrail.txt

Repair Boot Codes

If you are stuck with the MBR boot sector error message, run the following in the Command Prompt. You can open it from Advanced Options of Recovery.

• To repair boot codes, run the following command - BOOTREC /FIXMBR
• To restore the boot sector, run the following command - BOOTREC /FIXBOOT

BOOTREC can only fix the Master Boot Record. If there is a problem with the partition table, it will not help.

Fix BCD errors

If you received BCD-related error, you need to use Bootrec command to fix the issue.

1. Execute the Bootrec /ScanOS command to scan for all the existing system installed on the computer.
2. Restart, and check if the problem is there no more. If no, then execute with rebuild option, i.e.  Bootrec /rebuildbcd

If you receive an output which says Total identified Windows installations: 0, run the following commands:

bcdedit /export c:\bcdbackup attrib c:\\boot\\bcd -h -r -s ren c:\\boot\\bcd bcd.old bootrec /rebuildbcd 

Once the execution is complete, you should receive a success message as Total identified Windows installations: 1D:\Windows. It will then ask “Add installation to boot list? Yes/No/All”,  Enter Y. Reboot and see if this Windows boot problems tip resolved the problem.

Replace Bootmgr

If the above solutions didn't fix the problem, its time to replace the Bootmgr file from drive C to the System Reserved partition. To do this, follow these steps:

1. Go to the Command Prompt via Advanced Options.
2. Change the directory to the System Reserved partition and run attrib command attrib-s -h -r.
3. Do the same in the system drive, i.e., where Windows is installed.
4. Rename the Bootmgr file as Bootmgr.old with ren c:\\bootmgr bootmgr.old
5. Copy the Bootmgr.Old file to the System Reserved partition.
6. Rename it back to bootmgr.
7. Restart the computer.

Restore System Hive

When you receive an error where it says that Windows cannot load the system registry hive into memory, then you must restore it from an alternate backup location.

You can either use the advanced startup or Emergency Repair Disk (ERD) to copy the files from the C:\Windows\System32\config\RegBack to C:\Windows\System32\config. It will almost, reset the registry to a different time where everything was working fine.

4] Error during Kernel Phase

Receiving error at this phase can be exhaustive. We already have covered a lot of scenarios in detail. Here are few to get you started:

• A Stop error appears after the Windows logo splash screen.
• A specific error code is displayed.
• The screen is stuck at the spinning wheel or dots
• A black screen appears after the splash screen.

Let us know if this helped you to resolve Windows boot problems.