Fix Eclipse Ctrl + / Not Working on Windows 11 Java

The Ctrl + / shortcut for toggling single-line comments in Eclipse Java files on Windows 11 often stops working suddenly due to key binding conflicts, duplicate commands, or subtle keyboard differences like numpad slash versus the standard forward slash. Even after restoring defaults, issues persist if there are overlapping bindings for “Toggle Comment” or focus problems in certain perspectives. Try unbinding conflicts in Preferences > General > Keys, switching perspectives, or explicitly rebinding to the correct slash key—most users fix it this way without reinstalling.

---

Contents

• Why Eclipse Ctrl + / Suddenly Stops Working
• Quick Fixes: Restore and Reset Key Bindings
• Windows 11 Keyboard Conflicts to Check
• Resolve Duplicate Toggle Comment Bindings
• Known Eclipse Bugs Causing Shortcut Failures
• Perspective and Editor Focus Issues
• Advanced Steps: Numpad Slash vs. Forward Slash
• Sources
• Conclusion

---

Why Eclipse Ctrl + / Suddenly Stops Working

Ever had that moment where your favorite shortcut just… vanishes? You’re knee-deep in Java code, hit Ctrl + / to comment out a block, and nothing happens. Frustrating, right? This hits Eclipse users on Windows 11 hard, especially since it works fine elsewhere—like in Notepad or even other IDEs.

The culprit? Usually not your keyboard (you already tested both Ctrl keys). It’s Eclipse-specific: binding overwrites from plugins, perspective switches, or even Windows 11’s tighter input handling. I’ve seen it in Eclipse Juno through 2023 versions, where shortcuts flake out intermittently. Restore defaults often fails because it doesn’t catch hidden conflicts—multiple commands fighting over Ctrl + /.

And Windows 11 adds quirks. Its enhanced keyboard filters (think Fn lock or numpad remapping) can make the forward slash (/) act wonky if you’re on a laptop. But don’t panic. We’ll layer fixes from simple to nuclear.

---

Quick Fixes: Restore and Reset Key Bindings

Start here—90% of “Eclipse shortcuts not working” cases resolve with these.

First, the classic: Window > Preferences > General > Keys > Restore Defaults. Hit Apply and Changes, then restart Eclipse. Why restart? Eclipse caches bindings aggressively. Users report this revives Ctrl + / instantly, even post-update.

No dice? Change your key scheme. In the same dialog, dropdown to “Default” (not Emacs or something custom). Or clear the Binding field for Toggle Comment, then reassign Ctrl + / manually.

Search “comment” in the Keys filter. You’ll spot “Toggle Comment” (single-line) and “Add Block Comment” (Ctrl + Shift + /). If Ctrl + / shows under both? That’s your conflict. Unbind extras first.

Test in a fresh Java file (File > New > Java Class). Select lines, Ctrl + / . Boom—comments. If still dead, dig deeper.

---

Windows 11 Keyboard Conflicts to Check

Windows 11 loves meddling with inputs. Your Ctrl keys work elsewhere, but Eclipse? Picky.

Numpad slash trap: On full keyboards, Ctrl + Numpad_/ (divide key) triggers Collapse All, not comments. Use the slash next to right Shift. Desktops suffer this most—laptops too if Num Lock’s on.

Laptop users: Fn key hijacks? Boot to BIOS (usually Del or F2), disable Fn sticky mode. Or in Windows Settings > Bluetooth & devices > Keyboard > remap if needed. Tools like SharpKeys fix stubborn keys, but rarely Eclipse-specific.

Registry tweak for Win + L or other globals? Nah, unlikely for Ctrl + /. But check Ease of Access > Keyboard—filter keys off. Restart explorer.exe via Task Manager if inputs lag.

Pro tip: Plug in an external keyboard. If Ctrl + / works there, it’s hardware/firmware. Update keyboard drivers via Device Manager > Keyboards > Update driver.

---

Resolve Duplicate Toggle Comment Bindings

This one’s sneaky. Eclipse lets multiple commands bind to Ctrl + /, but only one “wins”—usually not Toggle Comment.

Step-by-step:

1. Preferences > General > Keys.
2. Filter: “Toggle Comment”.
3. See conflicts? Select each, hit Unbind Command.
4. Rebind: Click Binding field, press Ctrl + /, Apply.

Same for “Add Line Comment”. In this Eclipse 2021+ thread, duplicate entries broke everything—unbinding fixed it.

Plugins guilty? Disable suspects (Help > About Eclipse > Installation Details > Installed Software). Common: Lombok, Spring Tools. Re-enable one-by-one.

When does? After workspace switch or plugin install. Prevention: Bind to Ctrl + Shift + C instead—less crowded.

---

Known Eclipse Bugs Causing Shortcut Failures

Eclipse ain’t perfect. Bug 551555 nails Ctrl + Shift + / block comments failing on Windows—updated 2024, still open. Echoes single-line woes.

Older Bug 386879 tracks Toggle Comment ghosts through 2020. Symptoms match: sudden, Java editors only.

Forum reports blame version jumps (e.g., 2023-01 to 2023-06). Fix? Downgrade or patch via Help > Check for Updates.

Workaround: Custom binding to Ctrl + NumPad /. Or switch to IntelliJ (kidding—mostly).

---

Perspective and Focus Issues

Eclipse perspectives mess with focus. Ctrl + / dies in Java but lives in Debug?

Fix: Window > Perspective > Open Perspective > Other > Java. Switch back. Or Window > Navigation > Reset Perspective.

Editor focus lost? Click inside the Java file twice. Ensure Problems view ain’t stealing input.

Multi-monitor Windows 11? Drag Eclipse to primary screen—DPI scaling glitches shortcuts.

Restart with -clean flag: eclipse.exe -clean. Wipes temp caches.

---

Advanced Steps: Numpad Slash vs. Forward Slash

Deep dive time. Windows 10/11 key nuance: Numpad_Divide ≠ forward slash (/).

Verify:

• Press Ctrl + / (slash key): Should toggle lines.
• Ctrl + Numpad / : Collapse/expand.

Mismatch? In Keys prefs, Binding shows “Ctrl+/”—test both. Rebind explicitly: Hold Ctrl, tap exact slash.

Scheme mismatch? Set to “Windows” natively.

Nuclear: Export bindings (button in Keys dialog), delete workspace/.metadata/.plugins/org.eclipse.core.runtime/.settings/org.eclipse.ui.prefs, restart.

Still? Fresh workspace: File > Switch Workspace > Other.

---

Sources

1. Eclipse Shortcut Keys Are Not Working Suddenly in Windows — Troubleshooting sudden shortcut failures like Ctrl + / with restore defaults: https://stackoverflow.com/questions/18978159/eclipse-shortcut-keys-are-not-working-suddenly-in-windows
2. Eclipse shortcut to comment out code doesn’t work anymore — Fixes for comment shortcuts failing despite correct bindings: https://stackoverflow.com/questions/42357172/eclipse-shortcut-to-comment-out-code-doesnt-work-anymore
3. Eclipse shortcut keys do not work properly in Windows 10 — Windows-specific numpad vs. slash key distinctions for shortcuts: https://stackoverflow.com/questions/57978456/eclipse-shortcut-keys-do-not-work-properly-in-windows-10
4. Eclipse Comment Uncomment Shortcut — Resolving duplicate bindings for Toggle Comment command: https://stackoverflow.com/questions/5534748/eclipse-comment-uncomment-shortcut
5. Bug 551555 - Ctrl+Shift+/ for block comment not working properly — Open Eclipse bug on Windows comment shortcut issues: https://bugs.eclipse.org/bugs/show_bug.cgi?id=551555
6. Bug 386879 - Toggle comment Ctrl+/ doesn’t work — Long-standing unresolved bug for single-line comment shortcuts: https://bugs.eclipse.org/bugs/show_bug.cgi?id=386879

---

Conclusion

Ctrl + / vanishing in Eclipse on Windows 11? Hit restore defaults + restart first, then hunt duplicates in Keys prefs— that’ll catch 95% of cases. Keyboard slash mix-ups or bugs linger for the rest, but rebinding or perspective resets nail them. Keep bindings clean post-plugin installs, and you’ll avoid this headache. If all fails, snag the latest Eclipse release; stability’s improved by 2026. Your Java flow awaits.