System thread exception not handled [SOLVED]

The SYSTEM_THREAD_EXCEPTION_NOT_HANDLED Blue Screen of Death error is one of the most common among Windows 10, 8 and 7 users. For this reason, we decided to make things clear about it, by explaining how to solve it once and for all.

This error is generally caused by incompatibility or malfunctioning of the drivers, and usually occurs after Windows 10 upgrades. For this reason, computer manufacturers recommend to always update all the installed drivers before starting the upgrade process.

However, if you’re reading this article it means that it is already too late, so we can just roll up our sleeves and solve it.

Let’s start with a question: are you able to log in your Windows account, or the blue error screen appears too early and prevent you from doing it? In the first case, you can skip reading the following paragraph (as it explains how to access the Windows Safe Mode), otherwise – unluckily – you will have to read that, too.

Log in to Windows 10 in Safe Mode with Networking

If you can not access your Windows environment due to the error, you will need to resort to the Windows Safe Mode. To do so, just follow the instructions on the official Microsoft documentation, i.e.:

1. Restart your PC. When you get to the sign-in screen, hold the SHIFT key down while you select Power > Restart.
2. After your PC restarts to the Choose an option screen, select Troubleshoot > Advanced options > Startup Settings > Restart.
3. After your PC restarts, you’ll see a list of options. Select 5 or F5 for Safe Mode with Networking.

If even the safe mode with networking doesn’t work, repeat the process, but at the step 3 select the option 4 or F4 (simple safe mode, instead of the networking one). Then you will use another PC to download and transfer the driver installation files.

If, despite all the attempts you fail to start your PC in Safe Mode, don’t despair! You can still try to log in using this alternative method:

1. Turn off the computer
2. Remove the battery (if it is a laptop with removable battery)
3. Unplug it from the current
4. Leave it unplugged for a few minutes
5. Hold down the power button for 5-10 seconds
6. Reconnect the power (but NOT the battery)
7. Turn on your laptop. Now it should start normally (if you removed the battery, you can now re-insert it at your convenience)

Which driver is causing the error?

Typically, at the right hand of the SYSTEM_THREAD_EXCEPTION_NOT_HANDLED text you find the name of a file, listed in brackets. This name is useful to figure out which file (typically related to a device driver) is causing the error. For example:

• SYSTEM_THREAD_EXCEPTION_NOT_HANDLED (nvlddmkm.sys)
  The error is caused by nvlddmkm.sys file,which is part of the NVIDIA display adapters drivers.
• SYSTEM_THREAD_EXCEPTION_NOT_HANDLED (atikmpag.sys)
  The error is caused by atikmpag.sys, which is part ATI display adapters drivers.
• SYSTEM_THREAD_EXCEPTION_NOT_HANDLED (wificlass.sys)
  The error is caused by wificlass.sys, which is part of the Cisco access point drivers.
• SYSTEM_THREAD_EXCEPTION_NOT_HANDLED (iaStorA.sys)
  The error is caused by iaStorA.sys, which is part of the Intel Rapid Storage Technology Driver.
• … and so on.

If the filename is not among the sample ones, you can still figure out which hardware device it refers via a quick search on Google.

Update faulty/incompatible drivers

Now that you have located the faulty or incompatible driver, you just have to update it. Here’s how to do it:

1. Type Device Manager into the Start menu search bar, then click on the first result:

2. As an example, suppose that the file which caused the error is nvlddmkm.sys. In this case, we need to update the drivers of our NVIDIA display adapter, so expand Display Adapaters section, click with the right mouse button on the NVIDIA GeForce GT 640 and select Update Driver Software:

3. Now select the entry Search automatically for updated driver software:

4. Wait for completion, then restart your computer.

The annoying error will be finally gone!

Oh no, the blue screen is back! What can I do?

First, verify that the file that caused the error is the same as before. If not, repeat the device drivers upgrade procedure for the new file.

Also, make sure that all your PC software is up to date; some manufacturers (such as ASUS) make available a program specifically designed to facilitate the updating of all the drivers, in a fast and automated fashion.

If even the update of all the drivers didn’t fix the error, you can try to rename the faulty file (typically, you will find it in the windows\system32\drivers folder), for example by replacing the .sys extension with .old. However, this is a potentially risky (and meant to be temporary) workaround, recommended only for advanced users.

For any question and clarification on the subject, feel free to leave a comment in the form below.