4 Fixes to BSoD Error 0xC000021A on Windows Server 2012 R2

The error: 0xC000021A on Windows Server 2012 R2

0xC000021A is a common error in all Windows versions. Not only in Windows Server 2012 (R2)/2016, you may also encounter 0xC000021A on Windows 10. Sometimes, the “Preparing Automatic Repair” screen appears. However, it does nothing, only leaving you Windows Server 2012 R2 automatic repair loop. How frustrating it is!

Why does 0xC000021A error occur? There are 3 main causes responsible for it:

• Recently installed an incompatible program or driver
• Windows Update error
• Damaged system files

How to fix stop code 0xC000021A in Server 2012 R2

In this part, I’ll show you four quick fixes to Windows Server 2012 R2 boot loop error - 0xC000021A. Let’s get started.

👉 Fix 1: uninstall recently installed software or driver
👉 Fix 2: remove pending updates with DISM command
👉 Fix 3: run System File Checker
👉 Fix 4: perform System Image Recovery
👉 Precaution: backup Windows Server 2012 R2 before errors occur

Fix 1: uninstall recently installed software or driver

Since Windows Server 2012 R2 can’t boot normally, you should first boot into Safe Mode and then uninstall the software or driver.

★ Boot Server 2012 R2 to Safe Mode

1. Power on the server and power it off immediately when you see the first screen.
2. Power on the server again. Turn it off when the first screen shows up.
3. When you start the server the third time, it will initiate “Preparing Automatic Repair”. This may take 2 to 5 minutes.
4. Then it will boot to Recovery Mode. Click Troubleshoot > Startup Settings > Restart.

5. Your server will boot into the Advanced Boot Options menu. Select Safe Mode and press Enter to open Windows Server 2012 R2 in Safe Mode.

★ Uninstall recently installed software

1. Click Start > Control Panel > Programs and Features.
2. To order the programs by installed date, click Installed On to have the most recently installed programs on top. Then remove the last program in the list.

★ Uninstall recently updated drivers

1. Right-click the Start menu. Then select Device Manager.
2. When Device Manager opens, locate the problematic driver and right-click it. Then click Uninstall.

When you finish, restart your server in normal mode. Check if error 0xC000021A in Server 2012 R2 is fixed. If not, try the next fix.

Fix 2: remove pending updates with DISM command

If error 0xC000021A appears after Windows fails to install a new Windows Update, in most cases the update will keep failing and you will be stuck in an endless loop of restarting. Follow the steps below to fix it:

1. Boot Server 2012 R2 into Recovery Mode as mentioned in Fix 1.
2. Click Troubleshoot > Command Prompt.
3. When Command Prompt opens, type DISM /image:C:\ /cleanup-image /revertpendingactions and press Enter to rollback the update.

Tip: This command assumes that your Windows installation is on drive C. If it is on a different drive, change the drive letter.

4. Restart your server and see if it now boots successfully.

Fix 3: run System File Checker

System File Checker (SFC) checks integrity of protected system files. If some of them are corrupted or missing, SFC will replace them with correct versions located in C:\Windows. Learn how to run System File Checker as follows:

1. Open Command Prompt as you do in Fix 2.
2. In the Command Prompt window, type SFC /Scannow and press Enter.

3. When System File Checker completes, restart your server to see if the problem 0xC000021A still exists.

Fix 4: perform System Image Recovery

If you have created a full server backup before you experience error 0xC000021A in Server 2012 R2, you can fix this error via System Image Recovery.

1. Insert Windows Server 2012 R2 installation media into your server and boot from it.
2. At the Windows Setup screen, click Next. Then click Repair your computer.

3. At the Choose an option screen, click Troubleshoot > System Image Recovery.
4. The Re-image your computer wizard will detect the latest available system image on your server. You can use it or choose another system image taken before error 0xC000021A occurs. Then follow the wizard to restore your server.

Precaution: backup Windows Server 2012 R2 before errors occur

In addition to error 0xC000021A, you may encounter other server errors, such as stop code 0xc00002e2, Windows Server 2012 R2 stuck on loading screen, etc. To ensure you always have a way to restore your server to a normal state, you’d better create a scheduled backup for Windows Server 2012 R2.

Since Windows Server Backup has many limitations, like 2 TB limit, limit number of backups, etc., I’d like to recommend the best backup software for server – AOMEI Backupper Server. It is embedded with abundant features to meet all your demands concerning server backups:

• It enables you to create System/Disk/Partition/File Backup. You can also create Cloud Backup to backup important files to AOMEI Cloud.
• You are allowed to run automatic backups in five schedule modes: Daily/Weekly/Monthly/Event triggers/USB plug in.
• Various backup destinations are supported, including internal/external hard drives, network share and NAS devices, etc.
• It runs well on Windows Server 2003, 2008, 2012, 2016, 2019, 2022 (including R2), SBS 2003, 2008, 2011 and Windows PC systems.

Don’t hesitate to download this powerful server backup software. After you install it on your server, you can use it to backup Windows Server 2012 R2 easily.

To sum up

There are four quick fixes offered in this page to help you resolve 0xC000021A on Windows Server 2012 R2. You can pick up one according to your situation. To better protect your server OS and data, you can make use of the best Windows backup software AOMEI Backupper.

Actually, AOMEI Backupper is not only a backup utility but also a specialized cloning tool. It enables you to clone hard drive in Windows Server 2016 and clone C drive to SSD in Server 2019, etc. Download it now to discover more!