Why does copy and paste suddenly stop working on my Mac?

Usually the macOS pasteboard server (pboard) got into a bad state. Run `killall pboard` in Terminal to restart it. If only one app is affected, that app is the cause — quit and reopen it.

Does killall pboard delete my files?

No. It only restarts the background process that holds the clipboard. You lose the single item currently on the clipboard, nothing else.

Why does my old clipboard text paste instead of the new one?

The copy step failed silently, so the destination app fell back to the previous pasteboard contents. Re-copy the new text, or check that the source app isn't blocking the pasteboard.

Can a clipboard manager cause copy/paste to break?

A poorly written one can lock the pasteboard. A signed, local manager that simply observes the pasteboard (like ClipHistory) avoids this.

Why Copy and Paste Stops Working on Mac

You hit Cmd+C, switch windows, hit Cmd+V, and nothing happens. The old text pastes, or nothing pastes at all. This is one of the most common macOS annoyances, and almost every cause has a fast fix.

What actually holds your clipboard on macOS

macOS doesn't store the clipboard inside the app you copy from. A background process called pboard (the pasteboard server) holds it. When you copy, the app hands the data to pboard; when you paste, the destination app asks pboard for it. If that process gets into a bad state, copy and paste silently fail everywhere at once.

That single detail explains most clipboard outages: it's rarely the app you're in, it's the shared service behind it.

Fix 1: Restart the pasteboard server

This resolves the majority of cases. Open Terminal and run:

killall pboard

The process relaunches automatically. Try copying and pasting again right away. Nothing is lost except the one item currently on the clipboard.

If that doesn't help, restart the window server's helper too:

killall WindowServer

Note that WindowServer will log you out, so save your work first.

Fix 2: The app is the problem, not the system

If copy/paste works in some apps but not one specific app, the culprit is that app. Try this order:

Quit and reopen the app (Cmd+Q, not just closing the window).
Copy from a plain app like TextEdit, then paste into the broken app. If that works, the broken app's copy function is failing, not paste.
Check for a pending update. Electron-based apps (Slack, some editors) occasionally ship a build that mishandles the pasteboard.

Fix 3: Clipboard managers and security tools

Some clipboard utilities, screen-recording tools, and enterprise security agents intercept the pasteboard. If you recently installed one, quit it and test. A well-behaved clipboard manager reads the pasteboard without locking it; a poorly written one can stall it.

A local, signed clipboard manager that simply observes the pasteboard (rather than holding it open) avoids this class of problem entirely.

Fix 4: Remote Desktop and virtualization

If the failure started inside Screen Sharing, a VNC session, a virtual machine, or a Remote Desktop window, the clipboard bridge between host and guest is the issue. Toggle the "share clipboard" setting in that tool off and back on, or reconnect the session. The host Mac's clipboard is usually fine.

Fix 5: Restart, then check Activity Monitor

A plain restart clears almost every transient state. If the problem returns within minutes every time, open Activity Monitor and sort by CPU. A runaway helper process pegging a core often correlates with a frozen pasteboard. Force-quit the offender.

How to stop losing what you copied

The frustrating part of a clipboard failure isn't the failure — it's realizing you lost the thing you copied an hour ago. macOS only remembers the single most recent item, so a glitch (or just copying something new) erases it.

A clipboard manager keeps a running history. With ClipHistory you get the last 150 unpinned items plus unlimited pinned ones, all stored locally on your Mac with no account and no cloud. Even if the system pasteboard hiccups, your history is intact, and Cmd+Shift+V brings it back instantly.

Quick checklist

killall pboard first — fixes most cases
Quit/reopen the specific app if only one app is broken
Disable recently installed clipboard or security tools
Toggle clipboard sharing in remote/VM sessions
Restart the Mac for persistent issues

Get ClipHistory for macOS

Stop losing what you copied. ClipHistory is a local, AI-powered clipboard manager for macOS — signed and notarized by Apple, universal binary, macOS 12+. One-time payment of $19.99 (12-month license, no auto-renewal). Download ClipHistory.