How to fix ERROR_INTERRUPT_VECTOR_ALREADY_CONNECTED (763 / 0x2FB / 0x800702FB) – Interrupt vector already connected

This status means an attempt was made to connect a device or driver to an interrupt vector that is already in use.
In plain terms: Windows cannot connect a second handler to the same hardware interrupt because it’s already claimed. This is typically a driver-level or hardware resource issue, not a system-wide failure.

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Error code equivalence (same status, different formats)​

Fact: 0x800702FB is the HRESULT-wrapped form of Win32 status 763.

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What this really means​

Windows devices communicate with the CPU through interrupt vectors.

• Each hardware interrupt has a vector number.
• Drivers connect their Interrupt Service Routine (ISR) to a vector.
• Only one ISR can be primary handler for a vector unless shared interrupts are supported.

ERROR_INTERRUPT_VECTOR_ALREADY_CONNECTED occurs when:

• A driver tries to connect to an interrupt vector already in use
• The vector does not support sharing, or driver failed to mark it shareable
• There’s a misconfiguration or race in hardware initialization

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Common real-world scenarios​

1) Legacy hardware without shared IRQs​

Cause:

• Old PCI or ISA devices
• Both trying to use same IRQ line

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2) Driver attempting multiple connects​

Cause:

• Driver re-initializes without disconnecting previous ISR
• Hot-plug or resume from sleep triggers repeated connect

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3) Misconfigured ACPI / PnP resources​

Cause:

• BIOS or ACPI assigned the same vector to multiple devices
• OS tries to connect second device to already claimed vector

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4) Virtual machines or emulators​

Cause:

• VM device tries to attach to a vector already in use by host or another virtual device

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5) Filter or layered drivers​

Cause:

• Multiple drivers attempting to hook the same hardware interrupt without proper sharing flags

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Real fixes & solutions (ordered and practical)​

Step 1: Restart system or driver​

• Temporary conflicts can occur during hot-plug or resume
• Restart releases interrupt vectors

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Step 2: Update drivers and firmware​

• Ensure device drivers support shared interrupts if applicable
• Update BIOS/UEFI to fix incorrect vector assignment

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Step 3: Check Device Manager for conflicts​

• Device Manager → View → Resources by type
• Look for IRQ conflicts
• Disable unused devices sharing same vector

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Step 4: For driver developers​

• Use IoConnectInterruptEx with proper InterruptSharing flags
• Disconnect previous ISR before reconnecting
• Validate vector availability

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Step 5: Check ACPI / hardware configuration​

• Ensure no two devices claim the same non-shareable vector
• BIOS settings may allow manual IRQ reassignment

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Step 6: Virtualization environments​

• Ensure virtual devices are assigned independent interrupt vectors
• Update virtual hardware drivers to support shared interrupts if needed

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Related interrupt / hardware statuses​

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Practical diagnostic checklist​

• Which device triggered the status?
• Does the system report IRQ conflicts in Device Manager?
• Are drivers up-to-date and support shared interrupts?
• Did the issue occur after hot-plug, resume, or driver reload?
• Are multiple devices using the same hardware vector?

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Important clarification​

ERROR_INTERRUPT_VECTOR_ALREADY_CONNECTED is a driver-level resource conflict.
It indicates:

The requested interrupt vector is already claimed by another driver or device.

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Action is only required if:

• Device fails to function properly
• Conflicting devices exist

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Note​

• For end users: update drivers, check Device Manager, restart system
• For developers: ensure ISR connection logic handles existing vectors and uses sharing flags correctly