PC DRIVER_POWER_STATE_FAILURE (0x9F): The Sleep and Wake Crash
In plain English: DRIVER_POWER_STATE_FAILURE (0x9F) means a device driver did not answer when Windows told that device to power down or wake up. Windows waited, got no proper reply, and stopped with a blue or black screen to avoid leaving the device and the computer in a broken state.
First safe step: Note the timing first: write down whether the crash happens as the PC sleeps, wakes, or shuts down, then unplug outside devices for one test.
DRIVER_POWER_STATE_FAILURE (0x9F) means a device driver did not answer when Windows told that device to power down or wake up. Windows waited, got no proper reply, and stopped with a blue or black screen to avoid leaving the device and the computer in a broken state.
That timing is the clue that sets 0x9F apart in the plain English guide to blue and black screen stop codes. Did the crash happen as you closed the lid, let the computer sleep, woke it, or shut it down? Write that moment down before you change anything.
You do not need to guess or replace drivers at random. The guide below uses Device Manager to hunt one device at a time, in plain steps, checking the likely device first and testing after each change so you can tell what actually helped.
Part of the Blue Screen and Black Screen Stop Codes in Plain English series, the pillar guide for this cluster.
What this code means and why it shows up around sleep
DRIVER_POWER_STATE_FAILURE (0x9F) means Windows told a device to change power, and its driver did not answer in time. The device stayed on when it should have slept, or stayed asleep when it should have woken. Windows could not finish the change, so it stopped and showed the blue or black screen.
A driver is the small program that lets Windows talk to a device, such as a Wi-Fi adapter, graphics card, or Bluetooth adapter. When Windows says sleep or wake, the driver has to pass that order on and confirm it is done. If it stalls or answers wrong, the whole power change stalls with it.
That is why the timing matters so much. This crash usually appears when you close the lid, choose Sleep, use Hibernate, wake the computer, restart it, or shut it down. Those moments force many devices to change power at once. One device that does not change can block all the rest.
On its own, this code does not mean your files are lost or your hard drive has failed. It points first to a device and its driver. It also differs from the freeze that ends in a crash when a driver takes too long to answer during normal use, because 0x9F is tied to a power change.
First, note the timing and remove outside devices for one test
Write down the exact moment the crash happens. Note whether it fails when the lid closes and the PC goes to sleep, when you open it and try to wake it, or when you shut it down. Add how often it happens, every time, most times, or only now and then.
Think back to what changed just before the crashes began. Note any new device you started using, or any driver update that arrived around then. If that timing fits, check first steps if a blue screen started right after an update before you change anything else on your PC.
Save your work, then unplug outside devices for one test. Remove USB hubs, docks, external drives, and printers, and leave them out while you repeat the same sleep, wake, or shutdown step. If the crash stops, one device you removed is now a suspect. If Windows has stopped one before, note it for the power and port tests for a USB device Windows has stopped.
Before the test, do a full restart so Windows starts clean. Select the Start menu, select Power, then select Restart. Do not use Shut down for this step, because a restart clears the current session more fully and gives the next sleep or shutdown a fair test.
Find the device that will not change power in Device Manager
Open Device Manager from the desktop. Right-click Start, then select 'Device Manager;' from the list that appears. Scan the full list slowly and look first for a small yellow triangle with an exclamation mark beside any device. That mark flags a device Windows already has a problem with, so write its name down.
Next, check four groups in this order. Click the small arrow beside Display adapters, then do the same for Network adapters, Bluetooth, and Universal Serial Bus controllers, the USB controllers group. These cover the screen, internet and wireless parts, and devices plugged into the PC, all parts that must change power for sleep.
Inside each group, read the names in plain terms. Under Network adapters, look for the Wi-Fi or Ethernet name. Under Bluetooth, look for the mouse, keyboard, or headphones you use. Under USB controllers, look for hubs and controllers, not every small entry at once.
If you find a warning mark, stop there for now. If you do not, start with a device in these groups that matches your timing note, a new device, or a device updated just before the crashes began. If a marked USB device has been stopped by Windows, the power and port tests for a USB device Windows has stopped can help you sort that separate fault first.
Right-click the suspect device name and select 'Properties;'. Open the 'Driver;' tab at the top of the small window that appears. Write down the full device name and the driver date shown there, and keep the note with your crash timing. Do not change any setting on this visit. You are only naming the suspect.
Work on one suspect only, in the order you wrote them down. After the next steps deal with that one device, repeat the exact action that crashed before, closing the lid, choosing Sleep, waking the PC, or shutting down. Record whether it crashed, then move to the next suspect only if you need to.
Device Manager | PC Error CodesCheck the power saving setting on the suspect device
Right-click the suspect device in Device Manager and select 'Properties;'. Look along the top of the window that opens for a 'Power Management;' tab, and select it if it is there. Not every device has this tab, and that is normal. If yours does not, close the window and leave the device unchanged.
On that tab, clear the tick beside 'Allow the computer to turn off this device to save power' and select OK. Clearing it stops Windows turning this device off to save power, so it cannot be left off when sleep or waking comes. Change only the suspect device, then repeat the exact action that crashed and note the result.
If the crash still happens, reopen the same tab and put the tick back before you try a different device. Restoring it keeps each test clear and keeps power saving on where it works. This is also the same power saving setting behind Bluetooth mice and keyboards that keep disconnecting, so a changed tick there can affect waking as well as sleep.
The second box, 'Allow this device to wake the computer;', matters only for a network adapter or an input device such as a mouse or keyboard. If you use that device to wake the PC, keep the box ticked. For all other devices, leave this box as you found it.
Fix the driver: update it, roll it back, or let Windows reinstall it
If the crashes began soon after this device got a new driver, undo that change first. In Device Manager, open the device, choose the 'Driver;' tab, and select 'Roll Back Driver;' if the button is not grayed out. Restart the computer. If the crash followed a Windows update as a whole, use the first steps if a blue screen started right after an update.
If there was no recent driver change, or rollback is not available, get a fresh driver from a source you can trust. Start with the support page for your PC maker or the device maker, and match your exact model and Windows version. Install it, then restart. Only if neither lists one, look in Windows Update under 'Optional updates;' as a second source.
As a last driver step, let Windows install the device again. In Device Manager, right-click the suspect device, select 'Uninstall device;', and do not tick any box that offers to delete the driver. Restart the computer. Windows should detect the device and install a driver again, so give it a few minutes before you test anything. This can clear a damaged install.
Skip driver updater programs and paid fix tools. They can push drivers for the wrong model, charge to fix a problem they have not proven, and add programs you did not ask for. Do not pay because a scan sounds urgent. The makers' sites and Windows give you every driver step above for free, and none of those paid tools is needed for this fix.
If it still crashes on shutdown or waking
Try one last power test: turn off fast startup. With it on, Shut down does not fully power the PC off. It saves part of the system and wakes from that saved state, so a shutdown crash can still be a sleep problem in disguise.
Open Control Panel, open Power Options, and select 'Choose what the power buttons do;'. Select 'Change settings that are currently unavailable;', clear 'Turn on fast startup (recommended);', and select Save changes. Then shut down, start the PC again, and repeat the sleep or shutdown test.
If the PC crashes in a loop before you reach the desktop, do not keep forcing restarts. Follow how to start in Safe Mode if the crash stops you reaching the desktop, then repeat only the earlier driver steps there. If it still crashes in Safe Mode, stop.
Get hands-on help if crashes also happen at random times, away from sleep, waking, or shutdown. Bring your notes on timing, the suspect device, and its driver date, so the helper does not start over.
Frequently asked questions
Does this code mean my files or hard drive are failing?
Not by itself. 0x9F points first to a device and its driver failing to complete a power change, not to lost files or a failed drive. If crashes also happen at random times away from sleep and shutdown, get hands-on help.
Should I use a driver updater program to fix it?
No. Driver updater programs and paid fix tools are not needed for this fix. Use a driver from the PC maker or the device maker, with Windows Update optional updates as a second source.
What if my device has no Power Management tab?
That is normal. Not every device has a Power Management tab. Skip that check for that device and move on to the driver steps for the same suspect device.
Neighbouring cases in this cluster: CRITICAL_PROCESS_DIED (0xEF): Windows' Own Engine Stopped.
Conclusion
If the crash still has one clear time, closing the lid, sleeping, waking, or shutting down, you still have the most useful clue. 0x9F is tied to that power change, so the timing narrows the hunt more than the code alone does.
Keep your note of that timing, the suspect device, and its driver date, even if no fix worked yet. That note turns the next step, whether it is one more test in Device Manager or hands-on help, into a short job instead of a fresh search.