Alcor Micro AU9410-based USB 3.0 hub, connected to laptop via USB-C adapter. After connecting a high-power external HDD, hub became hot to touch, disconnected, and re-enumerated as “Unknown USB Device (Device Descriptor Request Failed)” with PID FA00, FW FA04. Cooling down for 10 minutes restored normal operation. Permanent fix: used externally powered hub.
For a USB drive to be recognized, the following handshake must occur:
When you see "unknown fa00" with firmware FA04, the handshake fails at step 2. The host sees a device on the bus (gets the chip ID "FA00") but cannot read the descriptor table from the NAND. Why?
If Windows still calls it "FA00 Hot," you must override the driver.
Note: You may lose the ability to read obscure formats like xD cards, but SD and SDHC will work.
The message "Alcor Micro Unknown FA00 FW FA04 Hot" is a scary-looking but usually fixable driver issue. In 80% of cases, simply uninstalling the device, rebooting, and forcing the "USB Mass Storage Device" driver will restore functionality. In the remaining 15%, a legacy Alcor driver package is required. Only in the final 5% is the chip actually dead.
If you are currently looking at this error on an old laptop, try inserting an SD card. You might find that the reader works fine despite the warning—the "FA04 Hot" error sometimes appears only when no media is inserted.
Otherwise, follow the driver override steps above, and you will turn that "Unknown" device into a working storage drive.
Keywords used: alcor micro unknown fa00 fw fa04 hot, alcor micro driver fix, USB VID_058F FA00 error, FA04 firmware hotplug issue.
Alcor Micro "Unknown FA00 FW FA04" errors typically happen when a USB flash drive's controller firmware is corrupted or the chip is overheating. 🛠️ Quick Troubleshooting Fixes
Cool it down: If the drive feels hot, unplug it immediately and let it sit for 10 minutes.
Try a USB 2.0 port: High-speed 3.0 ports can sometimes cause voltage spikes on failing Alcor chips.
Check Device Manager: Look for "Generic USB Hub" errors or "Unknown Device" listings. 💻 Advanced Recovery (AlcorMP)
To fix the "Unknown FA00" error, you usually need to re-flash the controller using the AlcorMP (Mass Production Tool). alcor micro unknown fa00 fw fa04 hot
Identify the Chip: Download ChipGenius to find your specific Controller Part Number (e.g., AU6989SN).
Find the Tool: Search for the AlcorMP version that matches your controller and the FA04 firmware revision.
Low-Level Format: Use the tool to perform a "High Level" or "Low Level" format to reset the firmware block. Caution: This process wipes all data on the drive. 🔥 Why is it "Hot"?
Short Circuit: A hardware component inside has failed, drawing too much current.
Firmware Loop: The controller is stuck in a "write loop," causing it to max out its thermal limit.
Safety: If the drive is too hot to touch, stop using it. It is a fire hazard and likely physically dead. If you'd like to try the software fix, let me know: The Chip Model from ChipGenius (e.g., AU69xx)
If you need data recovery or just want the drive to work again Your Operating System (Windows 10, 11, etc.)
Understanding the Alcor Micro Unknown FA00 FW FA04 Hot Issue: Causes and Fixes
The "Alcor Micro Unknown FA00 FW FA04" error typically surfaces when a USB flash drive or SD card reader using an Alcor Micro controller malfunctions. Users often report that the device becomes "Hot"—meaning it is either physically overheating or showing up as a "Hot Plug" device that Windows cannot properly initialize. What Does the Error Mean?
When your system reports "Unknown FA00 FW FA04," it is failing to read the firmware (FW) on the Alcor controller chip.
FA00/FA04: these are specific error codes indicating a handshake failure between the controller and the NAND flash memory.
Unknown: The operating system recognizes a device is plugged in but cannot identify its capacity, file system, or name.
Physical Heat: If the drive is getting physically hot to the touch, it usually indicates a hardware short or a controller stuck in a high-power boot loop. Potential Causes Alcor Micro AU9410-based USB 3
Firmware Corruption: The internal software of the USB controller has crashed.
Incompatible Drivers: Windows is trying to use a generic mass storage driver that doesn't match the Alcor chipset.
Partition Table Loss: The "low-level" format of the drive has been wiped.
Hardware Failure: A physical component inside the USB stick has burned out, often causing the overheating. Step-by-Step Fixes 1. Hardware Cool Down and Port Swap Before trying software fixes, address the heat issue. Unplug the device immediately if it is hot. Let it sit for 10 minutes.
Plug it into a USB 2.0 port instead of 3.0 (blue). USB 2.0 provides lower voltage, which can sometimes stabilize a failing controller. 2. Use AlcorMP (Production Tool)
The most effective way to fix Alcor Micro errors is using the AlcorMP tool. This is a factory-level formatting utility.
Identify your chip: Use a tool like ChipGenius to find your specific Alcor controller part number (e.g., AU6989SN).
Download AlcorMP: Match the version of AlcorMP to your controller number.
Run as Admin: Open the tool, click "Setup," and then "Start." This will perform a low-level format and re-flash the FA04 firmware. ⚠️ Note: This will erase all data on the drive. 3. Update Drivers via Device Manager
If the device isn't physically broken, a driver reset might help. Right-click the Start button and select Device Manager. Expand Universal Serial Bus controllers. Find the "Unknown Device" or "Alcor Micro" entry. Right-click and select Uninstall device. Unplug the drive and restart your PC. 4. Check for Short Circuits
If the drive gets "Hot" within seconds of being plugged in, it is likely a hardware short. Check the USB connector for bent pins. Look for debris or lint inside the port.
If the heat persists, the NAND flash chip is likely dead, and the drive should be discarded for safety.
💡 Pro Tip: If ChipGenius cannot see the device at all while it's getting hot, the controller is likely fried. At this stage, data recovery is nearly impossible without professional lab equipment. For a USB drive to be recognized, the
If you’d like to try recovering specific data before formatting or need help finding the right AlcorMP version for your chip: Share the ChipGenius report
Mention if the drive is a specific brand (like Kingston or Transcend)
Let me know if the heat is constant or only when transferring files
To help you find the right software, could you tell me the "Controller Part-Number" provided by ChipGenius?
Alcor Micro is a Taiwanese semiconductor company famous for producing USB flash drive controllers. If you see Hardware IDs like USB\VID_058F&PID_1234 or references to FA00/FA04 in your device properties, you are dealing with a generic USB mass storage controller manufactured by Alcor.
When Windows fails to recognize it, labeling it an "Unknown Device," it usually means one of two things:
If the drive is recognized by the system's USB layer but fails to mount storage, you need to "re-flash" the firmware. Alcor provides tools for this, often called AlcorMP or AlcorMPTool.
Step 1: Identify the Chip Download a tool called ChipGenius or USBDeview. Run it while the device is plugged in. It will show you the exact Controller Model (e.g., Alcor Micro AU6989) and the NAND Flash type.
Step 2: Find the Firmware Search Google for "AlcorMP [Controller Model] firmware." For example, if ChipGenius says you have an AU6989, search for "AlcorMP AU6989 firmware."
Step 3: Reprogram the Drive
Note: This process will erase all data on the drive. Do not attempt this if you have critical data on the device without consulting a data recovery specialist.
Run lsusb and dmesg -w.
If you see ID 058f:fa00 Alcor Micro Corp., try:
sudo modprobe usb-storage
echo "058f fa00" | sudo tee /sys/bus/usb/drivers/usb-storage/new_id
Some older Alcor readers need uas blacklisted.
| Symptom | Likely fix | |----------------------------------------|-------------------------------------------| | Unknown, cool, no card inserted | Normal – insert card | | Unknown, cool, with card inserted | Driver or reformat card (FAT32/exFAT) | | Unknown, hot, with/without card | Hardware failure – replace device | | Shows as FA00 in Linux, no storage | Firmware corruption – needs MPtool (risky)|