Fix Driver Power State Failure
DRIVER_POWER_STATE_FAILURE, bug check 0x0000009F, means a driver was in an invalid power state, often as the PC slept, woke or shut down. Remove or update the driver you added most recently, look for warning icons in Device Manager, install Windows updates, and ask your PC maker for a BIOS or firmware update.
Checked October 30, 2026 against the manufacturer's own pages.
The short version
What to install and where it comes from. Every link goes to the manufacturer or Microsoft, never to a copy.
Official files only, nothing bundled
Step by step
Undo what changed last
Think about what you installed before the first blue screen: a new driver, a VPN or security tool, or a new device. Microsoft's first suggestion for this stop code is to remove or update recently added drivers and system services.
Find flagged devices in Device Manager
Right-click Start and open Device Manager. Look for any device with an exclamation mark. Open its Properties, check the Events tab for errors, then choose Update driver on the Driver tab.
Match the crash time in Event Viewer
Right-click Start, open Event Viewer, then Windows Logs, System. Look for critical errors logged in the same minute as the blue screen. The source or device named there tells you which driver to replace.
Install updates in the right order
Run Windows Update and include any driver items under Optional updates. Only if the faulty device still has an old driver, get the current one from your PC maker or the chip maker.
Test with power saving turned down
Open Control Panel, Power Options, Change plan settings and set Put the computer to sleep to Never for a few days. If the crashes stop, a driver is failing during sleep or resume, and you can switch sleep back on once it is updated.
Update the BIOS and run hardware checks
Ask your PC maker whether a newer BIOS or other firmware is available, and follow its instructions with a laptop on mains power. Run the maker's hardware diagnostics too, and remove any part you added recently.
Why sleep and wake trigger it
Every device driver has to move its hardware between full power and low power when Windows sleeps, hibernates or shuts down. If one driver holds on to a power request for too long, or a power change times out, Windows stops with 0x9F rather than risk a hang. Microsoft’s own worked example traces the failure to a driver for a USB input device, which shows how small the culprit can be.
Read the parameters if you want detail
Microsoft’s reference lists the first parameter of the stop code as the type of failure. A value of 0x3 means a device held a power request for too long. A value of 0x4 means the change timed out while waiting on Plug and Play. Write the code and its first parameter down when the blue screen appears, since they help when you contact your PC maker’s support.
Questions
Does the blue screen name the driver?
Sometimes. When Windows can identify the driver responsible, its file name is shown on the blue screen. Search Device Manager for the matching device and update or roll back that driver first.
What if Windows crashes before I can log in?
Start in Safe Mode from the recovery environment: Troubleshoot, Advanced options, Startup Settings, Restart, then press 4 or F4. Device Manager and Event Viewer both work there.
Is 0x9F a hardware fault?
Usually it is a driver that did not complete a power request in time. A newly added device or an old BIOS can be behind it, which is why Microsoft lists removing new hardware and checking firmware.
Do I need a debugger to fix it?
No. Microsoft's debugger notes are for programmers with access to the driver's code. The basic checks above are the ones it recommends for everyone else.