Written for Synergy 3 (v3.8.4) and Synergy 1 (v1.22.3), checked 20 October 2026.
Find the message you see below; each one starts with what to do.
For anything not listed, send us your diagnostic info: Getting diagnostic info and logs
Messages about your license have an article of their own: License messages
What follows depends on your product: Synergy 3 or Synergy 1
Synergy 3
For the Sorry, something went wrong. error message box, see: What to do when you see an error message box
Connecting
Already connected
Wait a minute: the message clears by itself once the primary computer lets go of an old connection from this computer. If it doesn't clear, another computer may be a copy of this one, for example one set up from the same disk image, so reset the settings on one of them: Local settings in Synergy 3: updates, appearance, login screen and config file
The message says the primary computer refused this computer because a computer with the same name is already connected.
Missing keyboard layout, or Missing keyboard layouts
Install the keyboard layouts the message names on this computer, so you can type in them here. If you don't need them, click Don't show again. Synergy 3 shows this when keyboard language sync is on and the primary computer uses a layout this computer doesn't have: International keyboards and keyboard language sync
Messages about verifying your computers
For Computer wants to connect, Connect to this computer?, New certificate from a computer, Can't verify a computer, Not connected and An older Synergy 3 can't connect, see: Encryption and verifying your computers
Messages on the Screen layout
For Can't connect yet, No primary computer selected., Computers overlap. and Computers have the same name., see: Arranging your computers
Starting
Can't start
What to do depends on the message in the box:
- Synergy 3 stopped as soon as it started. Click Try again. Synergy 3 tries 3 times by itself first. If it still can't start, please send us a diagnostic report from this computer: Getting diagnostic info and logs
- Synergy 3 can't start because it needs libraries this system doesn't have (Linux). Install the package built for your distribution and release: Installing on Linux
- Sharing is stopped because your administrator's settings can't be trusted. Ask your administrator to check them. or Sharing is stopped because your administrator's settings couldn't be read. Ask your administrator to fix them. How they do it: Locking down settings so users cannot change them
Stopped unexpectedly
Click Close. Synergy 3 has already started again, so sharing carries on. If it keeps happening (the box counts how many times), please send us a diagnostic report from this computer so we can find the cause: Getting diagnostic info and logs
Already running, Legacy core running or Core already running
Click Yes to stop the other program and start sharing your keyboard and mouse. What each one means: "Already running" message in Synergy 3
Messages about the background service
For Service version is out of date. and the other background service messages, see: Troubleshooting the background service in Synergy 3
macOS permissions
Click Open privacy settings, then find Synergy in the list and switch it on. The message closes by itself once macOS allows it. If it stays, see: Troubleshooting the macOS Device Control and Data Access or Accessibility permission
Synergy 1
For the Sorry, a critical error has occurred. error message box, see: What to do when you see an error message box
Connecting
Address missing
Type the server's name or IP address in Connect to: on the client, then click Connect. The server shows its address in its own Synergy 1 window, next to Suggested IP:.
A Client with your name is already connected to the server.
Give each computer its own name: stop Synergy 1, click the pencil button next to This computer's name: (Edit Computer Name), type a name no other computer uses and press Enter. Also make sure Synergy 1 is open only once on this computer. The window title is Synergy Connection Error.
A new client called '...' wants to connect
Click Add client to place the new computer in your layout, or Ignore to refuse it until Synergy 1 restarts. If Require client certificates is on, you'll see A new client called '...' has been accepted instead; add it to your layout with Configure Server. Arranging the layout: Arranging your computers
Client Refused
Update Synergy 1 on the computer at the address in the message, so it can send a TLS certificate: Updating to a new version
The server shows this when Require client certificates is on and a computer tries to connect without a certificate, which an older version may not be able to send. To let computers connect without one, click Preferences and untick Require client certificates on the Network tab.
Computer not approved
Give the fingerprint shown in the message to your administrator, who can add the computer to the approved list: Locking down settings so users cannot change them
Connecting to a new server, or New client connecting
Compare the fingerprints and click Yes only if they match. How: Encryption and verifying your computers
Missing Keyboard Layouts
Install the keyboard layouts listed in the message on this computer, so it can type the other computer's characters. If you don't need them, tick Don't show this again. More about keyboard layouts: International keyboards and keyboard language sync
Starting
The Core executable could not be started.
Reinstall Synergy 1 so its files and permissions are restored: Reinstalling or uninstalling
On a server, the message can also name the server configuration file. Check that your account can read it (and write it, unless you use your own config file), or choose a file you can read on the Config file tab of Configure Server.
Sharing can't start
Ask your administrator to fix the problem the message names; Synergy 1 can't share your keyboard and mouse until they do. How they fix it: Locking down settings so users cannot change them
Background service offline (Windows)
Click Retry. If it appears again, restart the Synergy service in the Windows Services app and click Retry once more. If you stopped the service on purpose, click Disable to run Synergy 1 without it (this turns off Use background service (daemon) on the Advanced tab of Preferences; without it, Synergy 1 can't control the login screen or UAC prompts). Ignore closes the message and changes nothing.
Synergy is already running
Synergy 1 is already open. Look for its icon in the notification area (the menu bar on macOS) and open it from there. If it won't open, restart it: Restarting the app
Please drag Synergy to the Applications folder, and open it from there.
On macOS, Synergy 1 won't run from the downloaded disk image. Drag it to Applications and open it from there: Installing on macOS
macOS asks to allow Accessibility
Synergy 1 closes until you allow it under Accessibility in System Settings. The steps: Troubleshooting the macOS Device Control and Data Access or Accessibility permission
Settings
Invalid Screen Name
Use only letters, numbers, _ and -, between 1 and 255 characters, and a name no other computer in your layout already has (Screen name already exists).
Read-only settings
Your account can only read the settings file named in the message, so changes can't be saved. Ask your administrator to change the settings, or open Synergy 1 as an administrator if you are one. On shared computers this is usually deliberate: Configure Synergy 1 for multi-user support
Filename invalid: Please select a valid configuration file.
In Server Configuration, the Config file tab points to a file that doesn't exist. Click OK and pick the right file, or untick Use a server config file.