How to fix QUOTA_UNDERFLOW BSODs (0x00000021) in Windows 10?

What is a blue screen of death?

A blue screen of death (usually abbreviated as BSOD) is the notorious blue screen error often displayed after a severe crash or fatal system error. Windows is unable to recover from the crash due to its severe nature; the system ends up in a state in which it is no longer safe to work. A blue screen of death is the main consequence of a stop error that makes the system crash and/or restart. Loss of valuable data is a likely outcome as programs are starved of time required to save their data. Back-ups become very handy in such scenariIssues with computer hardware or problems with the driver software (for its hardware) are usually the causes of a blue screen of death. Regular apps or standard software are incapable of causing a blue screen of death. This is because the operating system is built to be independent of crashes or freezes involving such programs.

The blue screen of death tends to be accompanied by a stop code and/or its symbolic name. This stop code is very useful as it can be used to identify and troubleshoot the specific blue screen of death. QUOTA_UNDERFLOW Blue Screen Errors (0x00000021) in Windows 10 is an example of such a stop code and its symbolic name.

QUOTA_UNDERFLOW Blue Screen Errors (0x00000021) in Windows 10

What is Quota_underflow?

A disk quota is a limit or value usually assigned by a system administrator that controls some limited part of the file system on various operating systems (Windows included). Usage quota (also known as Block quota) and File quota (commonly referred to as inode data) are the 2 basic types of disk quotas.

The usage quota controls or sets the usable disk space, and the file quota limits the number of the files and directories that can be created.

The quota_Underflow error occurs when the disk quota is mishandled by a system administrator and the stop message is presented. The appearance of the stop message coincides with the hard drive becoming unmountable.

The data saved on an unmountable drive is inaccessible. A comprehensive backup might be required for complete restoration of data when such an event occurs. However, advanced data recovery programs have also proved to be quite effective in recovering data in scenarios where a backup is unavailable.

Causes of blue screen quota_underflow errors in Windows 10

BSOD quota_underflow errors in Windows 10 can be caused by a variety of reasons including but not limited to one of the following:

• Wrongly configured, outdated or corrupted drivers

• Fresh software corrupting the system registry

• Presence of a virus or malware wreaking havoc on the operating system files or other Windows program files

• Driver conflict after installing new hardware

• Corrupted or deleted system files

• A damaged hard drive

• A damaged RAM (temporary memory)

Signs of Quota_Underflow blue screen errors

The quota_underflow blue screen error is usually indicated or preceded by one of the following:

• Display of STOP Error 0x21: QUOTA_UNDERFLOW

• Display of QUOTA_UNDERFLOW with the crashing of the current program window

• The system lagging or working sluggishly and a slow response to actions performed on the keyboard or mouse

• The appearance of the message stating that a problem has been detected and your system has been shut down to prevent damage to your computer… Your system also tends to crash with the appearance of the error code Error 0x21 when you are running a particular program

• The appearance of the message “The QUOTA_UNDERFLOW bug check has a value of 0x00000021. This indicates that quota charges have been mishandled…”

• Your computer screen regularly freezing for a particular duration (usually a few seconds) from time to time.

How to fix quota_underflow blue screen in Windows 10?

The following steps on fixing the quota_underflow blue screen in Windows 10 are excellent and carefully thought-out methods for troubleshooting or solving your problems:

1. Log in with a new or different administrator account:

This is to ensure that the issues you are experiencing are not specific to your current account. Try logging in with a different administrator account and observe if the problems persist. If you do not have a different administrator account, first create a new local account by doing the following:

• Click on the Windows start icon or press the Windows key on your keyboard

• Click on Settings, select Accounts, Select Family and other people

• Click on Add Someone else to this PC

• Now you will be required to input a username, password, password hint. After doing this, click on Next

Now that you have created a standard local account, do this to make this newly created account an administrator account:

• After clicking on Next, you will be returned to the screen displaying accounts, and you will see the newly created account. Click on that account (the one you have just created) and click on Change account type

• A new window will pop-up, and there change account type from Standard User to Administrator. Now click on OK.

Now restart your PC, sign in with the new administrator account this time and verify that your problems have ceased to exist.

2. Perform an intensive scan for viruses or malware on your system:

Now it is time we considered the possibility that the issues you are experiencing with your system might be due to an infestation of malware. It is a widely acknowledged fact that installation of a reputable antivirus and performing regular scans with it is a basic requirement for a safe or healthy PC environment.

Launch your antivirus and perform a full scan to detect and remove threats.

If you do not have any antivirus or you have an excellent one but feel it is struggling to live up to your expectations, consider installing an anti-malware program and also performing scans with it. A superb anti-malware program like Auslogics Anti-Malware might just detect threats missed by your main antivirus and help resolve your issues.

It is simply an excellent program designed to work smoothly with whichever antivirus brand you have running. This results in the provision of that extra layer of security that ensures the maximum protection possible for your system.

3. Update your windows operating system:

In Windows 10, your system automatically checks for updates and installs them. To check for any available updates now, do this:

• Click on the Windows start icon or press the Windows key on your keyboard

• Click on Settings. Select Update and Security

• Click on Windows update. Click on Check for Updates. Windows should now search for the available updates.

If Windows finds updates, install these updates. If Windows says your system is up to date, then it means you have all the updates currently available.

This process is not exactly a fix but it is a practice necessary to solve compatibility issues. If the problems continue to bother you after you have ensured your operating system is up to date, move to the next fix.

4. Update your system drivers:

Corrupt or outdated driver software is also a probable causes of quota_underflow blue screen in Windows 10.

Updating drivers is a long or tedious process as you are required to download driver software for every single piece of hardware. You also do not know which exact driver software is the cause of your problems. This process is even further complicated by the efforts involved in the search of the needed drivers.

For these reasons, we recommend you use an lternative method of updating drivers.

The usual method involves you noting your PC’s brand, launching your browser and paying a visit to your manufacturer’s homepage.

Navigate through the site using your system’s model or name to find the specific drivers for your PC. After downloading the drivers you found, install them by following these instructions:

• Press (and hold) the Windows key and press the X key almost simultaneously. You will be presented with a list of useful programs.

• Click on Device Manager to launch it.

• Find the problematic driver software (if any is present). Right-click on it and select Update Driver Software.

If you could not detect any problematic driver, simply perform this action on all devices until you identify the one(s) causing you problems.

Alternatively, you can use a superb program to update all your drivers and solve your problems. Auslogics Driver Updater is an excellent tool that would perform a full system scan on your device. After this scan, you will be provided with a detailed report of your system drivers. Now the option for automatically updating all drivers using a single click would be presented to you.

Updating drivers is generally not an easy process. However, with Auslogics Driver Updater, it becomes a ridiculously simple task even for computer novices.

5. Run Windows file checker:

System file checker is a useful tool that can scan for system files for corruption and restore damaged files. This is how to use the program:

• Click on the Windows start icon or press the Windows key on your keyboard

• Input command into the available search box. Right-click on Command Prompt and select Run as administrator to launch a Command Prompt window with administrator privileges. In case you are prompted with a permission dialog box, select Yes and move on.

• Input sfc /scannow and press the Enter key on your keyboard. System file checker now should start scanning for errors and other problems associated with system files.

• Follow the displayed instructions as applicable. Otherwise, close the program and move to other steps if nothing was found.

6. Remove junk and other unnecessary files:

First, we advise that you clean your system registry. This can be done manually but note that even mere editing your system registry is a task not to be undertaken lightly. Your PC might refuse to start up properly if you tamper with or delete the wrong files. This is why we recommend that programs perform the task of registry cleaning automatically instead of leaving the process to humans (who are more prone to errors).

Auslogics Registry Cleaner is an awesome program that can eliminate errors and crashes by removing, repairing and optimizing your Windows registry. It is one of the best FREE tools on the internet. It is also completely safe and easy to use. Download and install it now.

You can also use Disk clean-up to clear away some files:

• Click on the Windows start icon or press the Windows key on your keyboard

• Search for Command Prompt in the available taskbar. Right-click on the presented result and select Run as Administrator.

• You might be prompted with a permission dialog box. Select Yes and move on.

• After the program launches, input cleanmgr and hit the Enter key

• Disk Cleanup should now start calculating how much disk space you can recover. Finally, you would be presented with a list of checkboxes. The category Temporary files usually use up most of the available spaces in most scenarios

• Now tick the boxes of the categories you intend to clean. Select OK to remove them.

7. Remove installed software:

If you encountered problems just after you installed a new program, then that program might be the reason for the manifestation of the quota_underflow blue screen. Sometimes you connect a new piece of hardware (along with its software) that is not compatible with your PC and BSOD is the end result.

Disconnect any new hardware (and uninstall its corresponding software) and finally restart your PC.

If you simply installed some programs during the last few days, remove those programs.

Here is how to uninstall programs in Windows 10:

• Click on the Windows start icon or press the Windows key on your keyboard

• Click on Settings

• Select Apps

• Click on the program you intend to uninstall and select Uninstall

• Follow the displayed instructions to complete the process.

Sometimes even the removal of your antivirus might just be the solution to your problem. However, some antivirus programs cannot be completely uninstalled by the process described above, and advanced tools might be required to fully remove them.

8. Restore or reinstall windows operating system:

You can restore your system to an earlier point in time. That point in time should be one in which you did not see Quota_underflow blue screen error messages.

Restore points can be created manually but are normally formed when you install a new software or update your Windows. The process described here would lead to loss of apps, drivers and other valuable files added after the restore point was created. The important thing is that your personal files would be left untouched.

Follow these instructions to restore your system:

• Click on the Windows start icon or press the Windows key on your keyboard

• Input Control Panel into the available search box

• Search for Recovery in Control Panel. Click on it.

• Click on Open System Restore and select Next

• Carefully choose a reasonable restore point. After doing this, click on Next, then Finish.

If restore points are missing, then you might need to turn on System Protection to make them appear:

• Launch Control Panel and navigate to Recovery once more

• Select Configure System Restore. Select Configure and ensure Turn on system protection is selected

It will be quite strange if restoration of your operating system fails to solve your problem but stranger things have happened. Then you will need to explore advanced options for ending BSOD Quota_underflow problems. You can perform a clean boot. You can also reinstall Windows 10 and find out more about similar options here.

9. Fix hardware issues:

The last fix was the final one for cases of blue screen quota_underflow errors in Windows 10 caused directly by software-related actions. This time we are going to examine your hard drive for corruption or other problems and also verify that your RAM has not been corrupted.

Follow these instructions to check for hard drive corruption using chkdsk:

• Click on the Windows start icon or press the Windows key on your keyboard

• Search for Command Prompt in the available taskbar. Right-click on the presented result and select Run as Administrator

• After the program opens, input chkdsk /f and press the Enter key

• The scan for corruption on your hard drive would be performed now. Follow the instructions presented on the screen when necessary

Windows might present you with the option to repair if some fixable problems were found. Otherwise, you might need to replace your hard drive if you can confirm that it is physically damaged and cannot be repaired by any software process.

Checking your system memory or RAM for instability is a bit more complex. Follow these steps carefully:

• Click on the Windows start icon or press the Windows key on your keyboard. Input Windows Memory Diagnostic and press the Enter key to launch it. Alternatively, you can launch the required tool by pressing the Windows and R key almost simultaneously to open the Run app, then typing mdsched.exe into the available box

• Now you will need to restart your PC to carry out this test. Also, note that you will not be able to use your computer while the process is still in play. Save any important work first and finally, let your PC restart. Simply Click on Restart now and check for problems

• Your PC should restart and the diagnostic program screen would appear. This test might require a lot of time, so be patient. You can leave your system to do other things and come back to it anytime you want.

In theory, after the test is completed, Windows should automatically reboot and return to your desktop where you will be presented with the results. Do not worry if this does not happen. You can find out the result of your test by doing this:

• Right-click on the Windows icon and launch Event viewer by selecting it.
• Select Windows Logs. Click on System. Here you will be presented with a list of events.
• Click on Find (in the left pane)
• Input MemoryDiagnostic into the box and click on Find Next. Now you can view the result of your test usually located at the bottom of the window.

If an error was found, you should consider running an extended memory test to verify the results. If the result remains positive, then at least one of the RAM sticks or modules is faulty and needs to be replaced.

It is human nature to try to fix a problem while spending as little as possible. It is understandable and this is one important reason we outlined the software fixes first. The other reason involves the progression of their use and relative complexity to carry out.

We hope that this guide has been comprehensive enough to end your nightmare involving the quota_underflow blue screen in Windows 10.