Written for Synergy 3 (v3.7.2) and Synergy 1 (v1.21.4), checked 3 October 2026.
Product: Synergy 1 and Synergy 3
Operating system: macOS
If your mouse moves to your other computers from your Mac but your typing doesn't follow, quit and reopen the app that has turned on macOS Secure Input. The log names it, on the Mac and on the computer you moved to, in a line like this:
application "Example" is blocking the keyboard
macOS allows apps to turn on Secure Input when the user needs to type any sensitive information (eg. a password). This is a security feature which helps to prevent any malicious app from getting access to such information.
When an app turns it on, only that app can read the user's keystrokes. Synergy 1 and Synergy 3 are also unable to read keyboard input, and therefore can't send the keystrokes to your other computers.
Most of the time, this is fine because as soon as you have finished entering your password or other sensitive information, the app will turn off Secure Input and your typing will reach your other computers again.
However, some apps have bugs and they do not turn off Secure Input in some cases.
How to fix it
Quitting and relaunching the app named in the log will turn off Secure Input and let your typing through again.
If the log names the app as "unknown", open Terminal (Applications, then Utilities, then Terminal) and run the following command to see which application is using Secure Input. The number after kCGSSessionSecureInputPID is the app's process ID, which you can look up in the PID column of Activity Monitor:
ioreg -l -w 0 | grep SecureInput
If closing the app does not work, log out of macOS and log back in.
If logging out and in does not help, run the command below in Terminal. Save your work first: it logs you out straight away and closes every open app.
sudo killall loginwindow