A20 Errors: A Troubleshooting Guide GA S REGULAR Menu Lifewire Tech for Humans Newsletter! Search Close GO Software & Apps > Windows
Troubleshooting Guide for A20 Errors
An A20 error means that there's a keyboard-related issue
By Tim Fisher Tim Fisher Senior Vice President & Group General Manager, Tech & Sustainability Emporia State University Tim Fisher has more than 30 years' of professional technology experience. He's been writing about tech for more than two decades and serves as the VP and General Manager of Lifewire. lifewire's editorial guidelines Updated on December 17, 2021 Tweet Share Email Tweet Share Email Windows The Ultimate Laptop Buying Guide The "A20" error is reported by the POST when it detects a problem with the keyboard or the keyboard controller located on the motherboard. While it's possible that an A20 error could apply to something else, it's very unlikely. This issue applies to any PC keyboard hardware. The operating system isn't involved in generating this error message, so you could receive it no matter what OS you might be using. A20 Errors
Shutterstock The A20 error displays during the Power On Self Test (POST) process very soon after the computer is first started. The operating system has not yet loaded when this error message appears. The error message may appear in many ways, but these are the most common: A20Error A20A20 Error Some software programs may use an A20 error for something completely unrelated to a keyboard or keyboard controller issue. Stan is one example, where an "Error A20" means a video is unable to stream. How to Fix the A20 Error
Turn off the computer if it's on. Disconnect the keyboard from the PC. Verify that the pins on the keyboard connector aren't bent. If they are, you can attempt to straighten the keyboard connector pins yourself and try the keyboard again. To do this, first remove any dust or debris from the end where you see the pins. Then, with a paperclip or something else, like a pen, bend the connector pins to the point that they look straight again. Verify that the pins on the keyboard connector don't appear broken or burned. If any do, replace the keyboard. Also, verify that the keyboard connection on the computer doesn't appear burned or damaged. If so, the port may no longer be usable. Since the keyboard connection is located on the motherboard, you may have to replace the motherboard to resolve this issue. Alternatively, you could purchase a new USB keyboard. Plug the keyboard back in, making sure it is plugged firmly into the correct port. If you're still having troubles at this point, make sure the PS/2 port is clean and wiggle the connection around as you press it in. It's possible you may end up bending a pin just right so that the cable will connect correctly. If the A20 error persists, replace the keyboard with a keyboard that you know works. If the error disappears, the cause of the problem was with the original keyboard. Finally, if all else fails, there may be a hardware issue with the keyboard controller on the motherboard. If this is the case, replacing the motherboard should solve this problem. Buyer's Guide to PC Motherboards You might also be able to check that the controller chip is firmly in place. If it's socketed, it's possible it just needs to be pushed in further. More Information on the A20 Error
Some computers may let out a sequence of noises to indicate an error. These are called beep codes. See How to Troubleshoot Beep Codes if you need help finding the BIOS manufacturer and/or help to understand what the beep codes mean. It's also possible to identify the A20 error through a POST code using a POST test card. Was this page helpful? Thanks for letting us know! Get the Latest Tech News Delivered Every Day Subscribe Tell us why! Other Not enough details Hard to understand Submit More from Lifewire Phoenix Beep Code Error Troubleshooting How to Fix Ntdll.dll Errors in Windows [10, 8, 7, etc.] What Is a POST Code? (Power on Self Test Code) How to Fix Problems that Occur During the POST What Are Beep Codes? (BIOS Beep Code Definition) How to Fix a Privacy Error In Chrome What Is a Power on Self Test Card? How to Fix Code 41 Errors in Device Manager Troubleshooting Guide for Mscoree.dll Errors How to Fix Missing Hal.dll Errors in Windows XP How to Manually Test a Power Supply With a Multimeter How to Fix Kernel32.dll Errors in Windows How to Unlock a Keyboard That's Locked 4 Best Free Memory Test Programs (October 2022) AMIBIOS Beep Codes (What to Do When Your PC Beeps) How to Fix a Computer That Turns on but Displays Nothing Newsletter Sign Up Newsletter Sign Up Newsletter Sign Up Newsletter Sign Up Newsletter Sign Up By clicking “Accept All Cookies”, you agree to the storing of cookies on your device to enhance site navigation, analyze site usage, and assist in our marketing efforts. Cookies Settings Accept All Cookies