Fix: DRIVER IRQL NOT LESS OR EQUAL (kbdclass.sys) BSOD Error

The “DRIVER IRQL NOT LESS OR EQUAL (kbdclass.sys)” is a critical error going around the corner and has affected a lot of Windows users. The said error results from issues with Wireless Keyboards, (especially Microsoft wireless keyboards) and usually pops-up throwing a Blue Screen of Death (BSOD).

The “DRIVER IRQL NOT LESS OR EQUAL (kbdclass.sys)” generally occurs when users plug-in the Wireless Keyboard and presses any key or key combinations, their System prompts a BSOD with the said error message. Though the issue is unusual, there are few possible fixes available for it as well.

How to fix the “DRIVER IRQL NOT LESS OR EQUAL (kbdclass.sys)” error?

Before getting into the solution, let as briefly discuss and understand what is “kbdclass.sys”?

kbdclass.sys is a Windows driver that stands for Keyboard Class Driver. It handles all the keys (individually) or key combinations, ideally all the general settings of a keyboard.This Kbdclass.sys is found in Windows 8, 8.1 and Windows 10.

Note: Before we begin with the steps, try to log in to your System normally. However, if that is not a possible case, then boot into the Safe mode, navigate the Advanced Start up options screen and further follow the fixes from the list below.

FIX 1: Update driver:

An outdated or faulty Driver can trigger the “DRIVER IRQL NOT LESS OR EQUAL (kbdclass.sys)” error. Thus, the first method we will try to fix the error via Updating the Driver. For doing so, follow the steps given below:

The steps here will explain to you the process of updating the Driver through the Device Manager.

Firstly, press WINDOWS + X and select the option Device Manager from the context menu.
Now on the Device Manager window, locate and expand the option Keyboards.
Here from the keyboard drivers list, right-click on the device name mentioned there and then select the option Update Driver from the sub-menu.
Now on the next screen, click on the first option, i.e., Search automatically for updated driver software. Your System will further identify, download, and install the Driver’s latest version (if available). Follow the on-screen instruction to complete the process.

FIX 2: Rollback keyboard driver:

When Windows auto-installs an update for the HID Keyboard Device, by default the same automatic update alter the keyboard class code and end the user with the “DRIVER IRQL NOT LESS OR EQUAL (kbdclass.sys)” error. Here the solution is, rollback the HID Keyboard driver under the Human Interface Devices section. For doing so, follow the steps given below:

Firstly, press WINDOWS + X altogether and select the option Device Manager from the context menu.
Now on the Device Manager window, locate and expand the option Human Interface Devices by double-clicking on it.
Here locate the HID Keyboard driver, right-click on it and select the option Properties from the sub-menu.
On the Properties window, select the Driver tab from the vertical menu.
On the same menu, click on the Roll Back Driver tab and then click on OK.

Once you are done, reconnect your Wireless Keyboard and check whether it functions smoothly or if the error persists.

FIX 3: Reinstall the USB Controllers:

As per many suffered users, reinstalling the USB Controllers has resolved the “DRIVER IRQL NOT LESS OR EQUAL (kbdclass.sys)” error issue for them. Thus, we recommend you to try the same and check if it works for you. For doing so, follow the steps given below:

Firstly, uninstall the USB controller, with the following steps:

Press WINDOWS + X and select the option Device Manager from the context menu.
Now on the Device Manager window, locate and expand the option Universal Serial BUS Controllers by double-clicking on it.
Here right-click on the option Generic USB Hub and select Uninstall Device from the sub-menu.
Follow a similar process for any of the USB Root Hubs entries in the same list as well.
Once done, restart your system. Your Operating System will automatically reinstall the controllers into your computer.

FIX 4: Uninstall 3rd-party security software (if applicable):

One of the prime causes for the “DRIVER IRQL NOT LESS OR EQUAL (kbdclass.sys)” error is the conflict between the wireless keyboard driver and Webroot antivirus software. In this situation, we recommend updating the software to the latest version to avoid the error. Though, if the problem still exists after running the latest version Webroot Antivirus software, it is advisable to completely uninstall the application.

Now at times, after removing the Webroot Antivirus software, a lot of users still face the same error issue. Thus, it is advisable to use a dedicated removal tool (customized uninstall tool for AV programs from the manufacturer) that can capably remove all the files associated with Webroot AV.

FIX 5: Perform System Restore:

One of the highly effective fixes that will work for you, if the ones mentioned above will not, is performing System Restore. The process will restore your System to an earlier date when it was working smoothly without any traces of the “DRIVER IRQL NOT LESS OR EQUAL (kbdclass.sys)” error.

These were all the tried and tested methods that will help you in getting rid of the “DRIVER IRQL NOT LESS OR EQUAL (kbdclass.sys)” error successfully. Once you have resolved the same, you will be able to use your wireless keyboard without any problem swiftly.

Though all of the above-mentioned- fixes are tired, tested, and helpful. But if none of them works for you, then consider installing the latest Windows update and check whether it helps in your case or not. After reading this article if you have any queries or feedback, please write down the comment in the below comment box.