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Fix 'System C Drive Full' Error in Windows Server 2019/2016/2012

Are you receiving the system c drive full in Windows Server message? Then, you should check out the detailed steps to free up disk space, clean cache, and extend the C drive on your Windows Server.

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Updated by Tracy King on Jan 16, 2024

Why Is Main Drive C So Full

There are many reasons why you receive a  system c drive full in Windows Server message. Window versions 2019/2016/2012 suffer from these reasons. Sometimes you will also receive a low disk space warning. When this happens, some programs may not work properly, and you will need to fix the problem quickly. For now, let us analyze the reasons behind why the Drive C remains full:

  • Windows product many system junk files in C drive continuously. You will find them in the cache, logs, thumbnail, downloads, internet files, etc.
  • Many of you might know that temporary files or simply temp files can cause the system to crash or slow down. It mainly occurs with Windows Version 2019/2016/2012. If you don't delete these temp files, you will receive a full system c drive in Windows Server.
  • Besides, the Windows native backup, restore point, and updates can take up a large chunk of space.
  • If your computer memory is low, then your disk space will run low. So, you need to uninstall these big programs to free up space on your computer.
  • When you have a virus infection or malware, the system might show an erroneous system c drive full in Windows Server message.

So, it is better to check what is taking up space in your C drive or server system drive. If you are using Windows version 2019/2016/2012, you should follow this guide to fix system c drive full in Windows Server.

Five Ways to Free Up C Drive:

#1. Extend System C Drive
#2. Clean Up Junk Files, Temp and System Cache
#3. Delete Windows. old from Windows Server Computers
#4. Transfer or Migrate Installed Programs from C drive to Another Drive
#5. Clean Up Virus

How to Fix 'System C Drive Full' Error in Windows Server Computers

Please, go through the following guide and resolve the system c drive full in Windows Server issue:

#1. Extend System C Drive

The most efficient way to fix the system c drive full in Windows Server problem is adding more free space to C drive from other partitions. Unfortunately, the native Disk Management system in Windows can't help you. You have to run a third-party software like EaseUS Partition Master Server Edition to extend system c drive space in simple clicks. What's more, the Partition Master allows you to resize, move, migrate, and change labels. Also, this software doesn't require deleting or formatting any existing partitions. It can extend the target drive even when there is no unallocated space on the disk.

EaseUS Partition Master Enterprise


Your trustworthy Windows Server disk manager.

Extend System drive, combine/split partitions.
Clone disk, migrate OS to HDD/SSD.
Convert MBR to GPT, GPT to MBR, no data loss.
1-click adjust disk layout, create volumes at one time.

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Option 1. Extend System C drive with unallocated space

  1. 1. Right-click on the System C: drive and select "Resize/Move".
  2. 2. Drag the system partition end into the unallocated space so to add it to the C: drive. And click "OK". 
  3. 3. Click "Execute Task" and "Apply" to execute the operations and extend the C drive.

Option 2. Extend System C drive without unallocated space

  1. 1. Right-click a big partition with enough free space on the system disk, select "Allocate Space".
  2. 2. Select the system drive at the Allocate Space From (*) To section, and drag the end of System C drive into the unallocated space. Click "OK" to confirm.
  3. 3. Click "Execute Task", it will list the pending operations, and click "Apply" to save the changes and extend the C drive.

0:00-0:26 Extend System Drive with Unallocated Space; 0:27-0:58 Extend System Drive without Unallocated Space.

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#2. Clean Up Junk Files, Temp and System Cache

Your computer's storage space requires regular cleanup to run smoothly. Also, regular system cleaning will help stop system c drive full in Windows Server message from popping up. Let us look at the different methods for cleaning up your cache, temp files, and recycle bins.

Method 1 - Delete System Junk Files using Disk Cleanup

Disk Cleanup is one of the best tools to delete all junk files from Windows.

  • Search for Disk Cleanup from the search bar and then select C drive and then press OK.

select drives to clean up

  • From the Disk Cleanup tab, select the checkboxes for the file types you want to delete. Next, press OK and remove the junk files from your PC.

Cleaning Your Browser And Thumbnail Caches

Browser and thumbnail caches consume huge memory space. It is always preferable to do it from the browser because you can get more control. It will also stop system c drive full in Windows Server message.

Open your internet browser and select browsing history, cookies, cached data files, and tabs recently closed. After that, press the Clear button to clean the cache.

clear browsing data

Clearing Temporary Files

Programs store temporary files on your hard drive. Over time, these files take up lots of space and cause the system to slow down. It is also the reason to receive the system c drive full in Windows Server message.

  • Press the windows button+R to open the run command. After that, enter this text:

open run command

  • Next, press OK, and open your temp folder.

open temp folder

  • Press Ctrl+A to select all. After that, press delete from your keyboard and click yes to confirm

delete multiple items

This will delete all your temporary files from the computer.

#3. Delete Windows. old from Windows Server Computers

You will always find the windows.old folder in the root of C after an upgrade. This folder contains a backup of your old program files, appdata, and folder. When you try to delete it, you are told you don't have permission. Assuming everything else is correct, you can delete the windows.old folder several GB size from your PC.

But you should note that this method will delete the previous Windows system backup if you plan to create a system restore point. So, you can choose to back up the OS to the external hard drive. You can choose EaseUS Todo Backup Enterprise to save a backup of your OS. It runs a reliable system backup software to back up the OS to an external hard drive. Besides, it comes with some innovative features and comes in four editions to meet the requirement of different business climes.

Let us look at how you can delete your windows.old folder and avoid system c drive full in Windows Server messages.

You may utilize the Disk Cleanup utility to delete large windows.old folder containing the old OS. But you can't access it without installing the Desktop Experience feature. So, you can use command-line tools, give full control to the administrators, and delete the item. Use the below common for achieving this feat:

>takeown /F c:\Windows.old\* /R /A /D Y

>cacls c:\Windows.old\*.* /T /grant administrators:F

> rmdir /S /Q c:\Windows.old

The Disk Cleanup tool too can perform this function. Follow the below steps to perform this function:

  • Open the file explorer on the Windows Start Menu. Next, click on the icon "This PC". Next. right-click on the drive containing Windows or the Windows.old folder and select "Properties" from the menu
  • Go to The General Menu and click the Disk Cleanup button to start the process.
  • Click Clean up system files
  • The window will display a list of system files that you can cleanup. Next, click on the box next to Windows Update Cleanup and confirm your selection by pressing the OK button. It will delete all data related to your previous version of windows, including the windows.old folder.

#4. Transfer or Migrate Installed Programs from C drive to Another Drive

You should always transfer some files from the C drive to another drive to save space. It will also avoid system c drive full in Windows Server message. However, any third-party software like EaseUS Todo PCTrans can help to migrate files as it fully supports all Windows OS with any laptops and computers. Plus, this software comes with an App Migration feature that allows you to change the installation location of their favored programs without reinstallation.

Step 1. Run EaseUS Todo PCTrans on your PC

Go to "App Migration" and click "Start" to continue.

Select app migration transfer mode

Step 2. Select programs to move from C drive to another drive

1. Tick the C drive and select programs (marked as "Yes") that you want to transfer.

2. Click the triangle icon to select another drive on your computer as the destination, and click "Transfer" to start the process.

select programs to transfer

Step 3. Finish the transferring

Wait patiently until the transferring process finishes and click "OK" to confirm. 

finish transferring programs from C drive to another drive

When it has done, you can restart PC if necessary. This will keep all changes on your PC and then you can run and programs from another hard drive without reinstallation.

#5. Clean Up Virus

You should always use antivirus software to clean up viruses and malware that showed system c drive full in Windows Server message.


It is always good to make use of disk space. That will leave enough space and avoid showing up system c drive full in Windows Server error message. However, you can reallocate disk drive space with ease by using EaseUS Partition Master Server Edition.

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About the Author

Updated by Tracy King

Tracy became a member of the EaseUS content team in 2013. Being a technical writer for over 10 years, she is enthusiastic about sharing tips to assist readers in resolving complex issues in disk management, file transfer, PC & Mac performance optimization, etc., like an expert.

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