Yeah, this one's annoying. You're trying to install a new network card or maybe a legacy PCI device, and Windows throws 0x000002FB at you. The exact message is ERROR_INTERRUPT_VECTOR_ALREADY_CONNECTED. It means the interrupt vector—think of it as a phone line for hardware to talk to the CPU—is already claimed by another driver. Two drivers can't share it without explicit support, so one gets blocked.
The Direct Fix: Unbind the Conflicting Driver
Skip the rabbit hole of reinstalling the OS or swapping hardware slots blindly. What's actually happening here is that a lower-level driver (usually a legacy one or a chipset driver) has already hooked that interrupt vector before the new device's driver had a chance. The real fix is to identify which driver is hogging it and temporarily unbind it.
- Press Win + R, type
devmgmt.msc, hit Enter. - Go to View > Resources by connection.
- Expand Interrupt request (IRQ). You'll see a list of IRQ lines and which devices are using them.
- Look for the failing device—it'll probably show with a yellow bang or not be listed yet. The error appears when you try to connect it, so you'll see its driver attempting to register.
- Find another device sharing the same IRQ number. Common culprits: old serial ports, LPT ports, or the system timer. Right-click that device, select Disable device.
- Restart your system. The freed IRQ should now be available for your new device.
If that doesn't work, you might need to manually assign the IRQ via the BIOS or UEFI settings. Reboot, enter setup (usually F2 or Del), and look for IRQ Resources or PCI IRQ Routing. Set the conflicting device to a different IRQ, or set the new device to a reserved one like IRQ 5 or 9. These are traditionally available on most x86 systems.
Why This Fix Works
The interrupt vector is a low-level mapping between hardware and the CPU. Windows's Plug and Play manager tries to assign unique vectors, but older drivers written for Windows XP or earlier may not follow the same protocol. They hook the vector directly via IoConnectInterrupt without checking if it's free. When your new driver calls the same function, Windows sees the vector is already occupied and returns 0x000002FB. Disabling the pre-existing device frees that vector without requiring a driver rewrite. The reason step 3 works is that the Windows Resource Manager shows you exactly which devices are mapped to which IRQ—no guesswork.
Less Common Variations
Sometimes the conflict isn't visible in Device Manager because it's a NT kernel driver that hooks the vector at boot time. In that case, check sysdm.cpl for Advanced > Startup and Recovery > Settings > System failure—enable Small memory dump. Reproduce the error, then open the .dmp file in WinDbg. Run !irp or !analyze -v to see which driver module claimed the vector. I've seen serial.sys and parport.sys cause this more than anything else—they're old and still present on modern Windows for backward compatibility, but they don't play nice with newer hardware.
Another variation: if you're on an AMD Ryzen system with a X570 or B550 chipset, the PCIe lane assignment can cause interrupt conflicts in certain BIOS versions. Update your BIOS to the latest stable release—manufacturers like ASUS and MSI have patched this exact bug in versions from late 2023 onward. The changelog often mentions “improved IRQ routing for PCIe devices.”
Prevention
Don't install drivers from Windows Update for legacy devices unless you have to. Use the manufacturer's signed driver instead. If you're adding a new card, check the manual for recommended slot placement—some slots share IRQs with onboard peripherals. Also, disable any unused ports in Device Manager or BIOS (serial, parallel, PS/2) before installing new hardware. That frees up vectors proactively. Finally, if you run VMs that pass through hardware, be aware that Hyper-V's hypervisor can pin interrupts, causing this error on the host when you try to install a different driver later. In that scenario, remove the passthrough device from the VM first.