Drivers · critical

How to fixDRIVER_IRQL_NOT_LESS_OR_EQUAL

IRQL driver - incorrect level

What this error means

A kernel driver accessed memory at an inappropriate interrupt level (stop code 0xD1). The driver named in a crash needs investigation rather than automatic deletion.

Applies to
Windows 11; Windows 10 interfaces may differ
Difficulty
Intermediate
Before changes
Some checks require restart or system changes

Documentation checked: 2026-09-28 · Editorial guide checked against the linked documentation; not tested on every hardware configuration.

Before you begin

Back up important files. Save your work and record the exact message before changing anything. If Windows cannot start, see the startup guide.

Work through these checks

0 of 4 complete
01Record any named driver
  1. Photograph the stop code and any .sys filename.
  2. Write down recent device-driver, peripheral, VPN or security-software changes.
What to expect

You have a lead that can be checked against installed devices.

If it does not help

If no driver is named, keep the dump for private analysis rather than guessing from the code.

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02Identify the device or software owner
  1. Find the corresponding device in Device Manager or the software’s support documentation.
  2. Record its driver version before changing it.
What to expect

The file can be associated with a specific vendor or package.

If it does not help

Do not delete a system driver file just because its name appears in a crash.

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03Test an appropriate driver change
  1. Use the vendor’s instructions to roll back a recent problematic update, or install the appropriate supported driver for that device.
  2. Make one change and test the same activity again.
What to expect

You can compare stability before and after that driver change.

If it does not help

If it persists, retain both driver versions and the crash times for support.

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04Escalate a recurring crash
  1. Provide the driver name, version history and stop code to support.
  2. If the machine cannot boot normally, use the startup guide before further changes.
What to expect

A dump analysis can identify the failing operation.

If it does not help

Do not run aggressive driver stress tools without a recovery plan.

Browse related errors

Possible causes

  • Incompatible driver
  • Corrupted INF file
  • Network or GPU driver

Sources & further reading