Keyboard Keys Not Working or Repeating: How to Tell Software From Hardware
Key not responding, typing twice or working only sometimes? Use TryYourGear's Keyboard Test to see what the browser receives and tell software from hardware.
A key that does nothing, one that types twice, one that only works when it feels like it: they all look like “a broken key”, but the cause can sit in several places. The switch under the keycap, the keyboard's electronics and firmware, the cable or wireless link, the operating system's keyboard settings, remapping or macro software, and only then the browser. Testing in the right order keeps you from replacing a keyboard that only needed a setting changed, or the other way round.
TryYourGear's Keyboard Test can check one thing: whether your browser receives a key press and a key release for each key. It shows you what arrived. It can't see what happened before the event reached the browser, so it narrows down where to look rather than proving a fault.
What this guide can and can't tell you
If a key registers in the test, the path from that key to the browser works at least some of the time. If it doesn't, the browser received nothing, and the cause could be the key, the keyboard, the connection or the system. The test can't tell you whether a switch is worn, whether there is an electrical fault or what the firmware is doing.
What the Keyboard Test actually shows
The on-screen keyboard is a simplified ANSI-style layout of 73 keys: Esc, F1–F12, the number row, the three letter rows, Shift, Ctrl, Win, Alt and Space. Each key is identified by `KeyboardEvent.code`, which names the physical position of the key rather than the character it types, so the same position lights up on QWERTY, AZERTY or a Spanish layout.
- A key is highlighted while it is held down: the page has received its key press and not yet its release.
- It turns green once it has been pressed at least once, so a pass over the whole keyboard shows which keys never registered.
- A “last events” list shows the codes of the latest presses, newest first. It lists presses only, not releases, and it has no timing.
- If the browser flags a press as automatic repeat, which is what happens while you hold a key, the page shows a warning naming the key.
While the page is open it blocks the browser's default action for Space, Tab and F1–F12, so you can test them without the page scrolling, changing focus or reloading. There is no numeric keypad, arrow cluster or navigation block in the drawing; those keys still appear in the list by code but don't light anything up.
Run the test and read what you see
Open the Keyboard Test, press the problem key slowly, one time, and watch both the highlight and the “last events” list. Then match what you see to a row.
| What TryYourGear shows | What it suggests | What it doesn't show |
|---|---|---|
| You press the key and nothing lights up, it never turns green and its code doesn't appear in the list | The browser received nothing for that position. The key, its switch, the keyboard, the connection or something in the system is stopping it before the page. | Which of those. Nothing here tells a worn switch from a loose connection. |
| The key lights up and turns green, but only some of the time | The path works intermittently. Press it ten times and count. Intermittent behaviour often points to the connection (cable, port, battery, wireless link) or to dirt or wear, but that is a lead, not a finding. | Why it fails when it does: a missed press leaves no trace in the test. |
| One slow tap adds the same code twice to the list | The browser received two separate presses. That is how a switch that bounces, or software that repeats input, looks to the page. | Which of the two it is, or how many milliseconds apart the presses were. |
| The repeat warning appears although you only tapped the key | The browser flagged automatic repeat, which it does for a key it believes is held down. Software holding the key, or a key that is physically stuck down, can look like this. If you were holding the key, a repeat is normal. | Whether the key is physically stuck. The test only knows which events arrived. |
| The key stays highlighted after you let go | The page received the key press but not the release. A key stuck down can do this. If you switched windows while holding a key, the page can also miss the release: press Clear results and try again. | Whether the key is physically stuck. |
| A different key lights up than the one you pressed | The keyboard, its profile or remapping software is sending another position's code. A layout difference doesn't cause this: the code names the physical position, so a key that types another letter on another layout still lights the same spot. | Where the remapping happens. |
| Some keys stay dark while you hold several together | The browser didn't receive all of them at once. Keyboards limit how many simultaneous keys they report, and a fault can look the same. | Which cause it is. The test doesn't detect ghosting by itself; it only shows which of the held keys arrived. |
MDN's reference explains the repeat flag the test relies on for the warning: it is set when a key is held down and the operating system generates repeated key events.
What the browser can't prove
- A failed switch. A missing or doubled press fits a worn or dirty switch, and it fits plenty of other things. The test can't look inside the key.
- Electrical faults or firmware behaviour. What happens inside the keyboard before it sends a key never reaches the page.
- Driver-specific problems. The test sees events after the operating system has processed them.
- Anything that happens before the event reaches the browser. The system can intercept some shortcuts, and function-layer keys, media keys and Fn combinations are often handled inside the keyboard and never sent to the computer.
- Ghosting or rollover limits. The test doesn't detect ghosting automatically. Holding several keys shows which ones arrived, and the interpretation is yours.
- How a key feels. A key that registers but feels sticky, mushy or inconsistent looks the same as a good one in the test.
Common causes and how they tend to show up
| Cause | How it may show up | What to try |
|---|---|---|
| Dirt or debris around a key | A key that sticks, misses or repeats. | Unplug the keyboard, turn it upside down and tap it gently, and wipe the outside. Microsoft's advice is to make sure no dirt is blocking keys or sensors. Don't pry off keycaps or use liquids unless the manufacturer says it is safe. |
| A worn or failing switch | One specific key that misses or double-types, on every computer. | Test the keyboard on another computer. If the same key fails there, the keyboard is the likely cause: check the warranty or the manufacturer's support. |
| The connection | Keys that fail at random, several at once, or a wireless keyboard that lags. | Try another USB port, connect directly instead of through a hub, replace the batteries or re-pair a wireless keyboard, and inspect the cable. These are checks Microsoft's keyboard troubleshooting page lists too. |
| The layout or input language | The wrong character appears, although the key lit in the test is the right one. | This is a system setting, not a fault: the test shows the physical position correctly while the typed letter is wrong. Check your input language and layout. |
| Accessibility features that filter keystrokes | Keys that ignore quick or repeated presses, or that need to be held longer. | Windows 11: Settings > Accessibility > Keyboard. Windows 10: Settings > Ease of Access > Keyboard. Filter Keys makes the keyboard ignore brief or repeated keystrokes (Microsoft Support). On a Mac: Apple menu > System Settings > Accessibility > Keyboard, where Slow Keys sets how long the Mac waits before responding to a key (Apple Support). |
| Key repeat settings | Letters that repeat too soon or too fast when you hold a key. | On a Mac, Delay until repeat and Key repeat rate control this (Apple Support). |
| Remapping, macro or manufacturer software | Wrong or extra keys, or keys that do several things. | Close or reset the software and test again. |
A practical order to follow
Test the key in TryYourGear
Press it slowly ten times. Note how many presses show up in the list and whether the highlight follows your finger. Press Clear results to start clean.
Try another application
Type the key in a plain text editor or another program. If it misbehaves there too, the problem is below the browser. If it works there but not in the test, click the page so it has focus and try again: the system or the browser can consume some shortcuts before the page sees them.
Try another port or connection
Unplug the keyboard, wait a moment and plug it into a different USB port, without a hub. On a wireless keyboard, replace the batteries or re-pair it. Then repeat step 1.
Rule out settings and software
Turn off Filter Keys (Windows) or Slow Keys (Mac), close remapping or macro software and check the layout. The table above says where.
Try another keyboard, or this one on another computer
This is the most informative step. The same key failing on another computer points to the keyboard; a keyboard that works there points back to the first computer's settings, drivers or connection.
Decide
Use the table below. It is a way to read your observations, not a diagnosis.
| What you observed | What it points to |
|---|---|
| Fails in the test, in other apps and on another computer | The keyboard itself: a switch, its electronics or its firmware. |
| Fails only on this computer and works on another | This computer's settings, drivers, port or software. |
| Fails only in one application | That application's own shortcuts or settings. |
| Fails on the wireless connection but works with a cable | The wireless link or the battery. |
| Fails at random everywhere | The connection or the keyboard. Keep a note of which key, how often and what the test showed. |
What to do with your result
The key registers in TryYourGear but not in an app
The browser does receive the key. Look at that app's own keybindings, any remap or macro that applies only there, and the input language the app uses.
It doesn't register in TryYourGear either
Go through the flow in order. If it fails on another computer as well, contact the manufacturer or the seller and tell them what you observed: which key, how often it fails, and what the test showed. Don't open the keyboard unless the manufacturer's guidance says it is safe.
Once every key registers, the Typing Speed Test shows how the keyboard behaves in a real typing run. It can't tell you why a key is missing, but a run with repeated or missing letters is a good reason to come back to this guide.
Summary
- Run the Keyboard Test and read the highlight, the green state and the “last events” list, one key at a time.
- A key that never registers, one that registers twice and one that appears held down are different observations. Each points to different places, and none of them proves a failed switch.
- Go in order: another application, another port or connection, settings and software, then another keyboard or computer.
- The test can't see below the browser and doesn't detect ghosting by itself. It narrows down where to look; it doesn't diagnose hardware.
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