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Startup & recovery · scoped error record
0x0000007B

INACCESSIBLE_BOOT_DEVICE: Windows lost access to the system partition during startup

Stop 0x7B is a startup/storage path failure; preserve recent storage, controller, firmware and driver changes.

Applies to: Windows startup stop-code / bug-check contextReviewed: 2026-09-17

What it means in this context

INACCESSIBLE_BOOT_DEVICE (0x7B) means Windows could not access the storage volume needed to continue startup. The cause can sit in storage/controller drivers, boot/storage configuration or hardware, so generic desktop app repair is not relevant.

Start here
  1. Record whether the error followed a storage/controller driver, firmware, cloning or hardware change.
  2. Disconnect nonessential external storage.
  3. Enter Windows Recovery Environment if available.
  4. Confirm the system drive is detected by firmware/BIOS before assuming Windows alone is at fault.
1

Use Windows Recovery Environment and Startup Repair first

Medium risk

Why: The machine cannot reach normal Windows, so supported recovery tools are the appropriate low-level starting point.

  1. Enter Windows Recovery Environment.
  2. Choose Troubleshoot > Advanced options > Startup Repair.
  3. Record whether Startup Repair finds or changes anything.
2

Reverse the recent storage/driver/update change when the timing is clear

Medium risk

Why: A controller or storage-path change immediately before 0x7B is stronger evidence than unrelated repairs.

  1. Use recovery options that match the trigger, such as uninstalling a recent update or System Restore when available.
  2. If a storage/controller setting was intentionally changed, restore the known-good supported configuration rather than experimenting.
Scope boundary

When not to use this record

If firmware does not detect the system drive or hardware diagnostics fail, stop software-only repair and investigate the drive/controller hardware. Avoid registry edits copied from unrelated 0x7B cases.

If it persists

If the drive is detected and recovery tools cannot restore startup, collect the exact storage/controller context before considering advanced offline repair or reinstall.

Evidence

Reviewed source

Related authority records

Continue with the same failing system

These links share the same component or repair context; they are not generic keyword suggestions.

GuideWindows 11 stuck in a restart loop: use recovery options in the least disruptive order

Move from Windows Recovery Environment and startup checks toward restore or reinstall only when the loop persists.

GuideWindows 11 won’t start: when to use Startup Repair

Use Windows Recovery Environment and Startup Repair for genuine startup failures, not ordinary app crashes.

Error0x00000050 — PAGE_FAULT_IN_NONPAGED_AREA: invalid system memory was referenced

Microsoft defines bug check 0x50 as an invalid system-memory reference; driver and memory evidence matter.

Error0x0000007E — SYSTEM_THREAD_EXCEPTION_NOT_HANDLED: an unhandled kernel thread exception

Bug check 0x7E means a system thread generated an exception that the error handler did not catch.

Error0x0000009F — DRIVER_POWER_STATE_FAILURE: driver stuck in a power transition

Microsoft defines bug check 0x9F as a driver in an inconsistent or invalid power state.

Error0x000000D1 — DRIVER_IRQL_NOT_LESS_OR_EQUAL: a kernel driver made an invalid high-IRQL memory access

Microsoft describes bug check 0xD1 as a kernel-mode driver accessing pageable or invalid memory at an IRQL that was too high.