Device Manager Needs to Be Checked For Error 40

Whenever system comes up with error 40, we simply need to go to the windows device manager. So, we can click on “Start” button and type "sysdm.cpl" in the run command. After this we need to click “Ok”. The System Properties window will open and we need to click on the “Hardware” tab. Here, we will see an icon called Device Manager. Under this we need to locate the causing device. Now we need double click on that icon and “Properties” option will come up. We need to look for the “Device Status” box and need to find a tab called “General” which will show the any recent error regarding any device drivers.

Generally, error 40 looks like "Windows cannot access this hardware because its service key information in the registry is missing or recorded incorrectly (Code 40)". It happens when there are invalid driver service subkeys in the registry. Error 40 also happens, if the system is unable to locate the device.

In order to troubleshoot error 40, we need to use a PC driver updating utility, so that we could find the accurate driver for the device. Then we need to uninstall the faulty driver. For this we need to locate the device's properties box and then need to choose the “drivers” tab. Once we locate the right device type, we can right click on the icon and click on “Scan” for any hardware changes. Now “Add Hardware” wizard will pop up which will re-install the driver. Now we need to click on the “General” tab under the device's properties box in the Device Manager) and then we need to select “Troubleshoot” to launch the troubleshooting wizard. We need to follow the screen and error 40 will be finished.