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OpenCode connection failures usually come from a wrong saved server URL, a conflicting port or hostname setting, or a web server that is listening somewhere other than the address you opened. Desktop can start its own local server or connect to a configured URL, while opencode web starts a separate browser-accessible service. Identify which setup you are using, then follow the matching steps below.
First identify which OpenCode connection is failing
The same “Connection Failed” symptom can describe different network paths. Determine where the server process is running before changing settings.
| Setup | Where the server runs | What the client connects to | Typical network scope | Authentication consideration |
|---|---|---|---|---|
| Desktop built-in server | Started by OpenCode Desktop on the same computer | Desktop’s default local server selection | Usually local to that computer | No separate remote-server password is normally involved |
| Desktop with a configured server | A separately running OpenCode server, including one in WSL | The URL saved in Desktop’s server picker | Local machine, WSL, or another reachable host | Required when the server is exposed beyond localhost |
| Browser web app | Started with opencode web |
The URL printed in the terminal | 127.0.0.1 by default; broader if you change the hostname |
Use a password when allowing non-local access |
OpenCode’s official troubleshooting guide confirms that Desktop can either start its own local server or connect to a server URL you configured. OpenCode troubleshooting documentation
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Desktop shows “Connection Failed” or stays on the splash screen
1. Check the saved server in the Server picker
- Open the OpenCode Desktop Home screen.
- Click the server name and status dot to open the Server picker.
- In the Default server section, click Clear.
- Restart Desktop and let it use its built-in local server.
This removes a stale or mistyped URL without changing project files. If Desktop starts normally after clearing the selection, the saved endpoint—not the Desktop interface—was the problem. Re-enter a server URL only after confirming that the server is running and that the address is reachable from the Desktop machine.
Check the complete address, not only its hostname. A server on port 4096 is a different endpoint from the same hostname on another port, and an old WSL address may no longer identify the current virtual machine. Keep the protocol, hostname, and port together when copying an endpoint into the picker.
2. Temporarily remove the server configuration
A project or user configuration can force Desktop toward an invalid port or hostname. Close Desktop, make a backup copy of opencode.json or opencode.jsonc, and temporarily remove the entire server section, including any server.port and server.hostname entries. Restart Desktop and test again.
Removing the whole section is a diagnostic step. It does not prove that either property is wrong; it isolates configuration from the connection path. If the application works afterward, restore settings one at a time and test after each change so the offending value is identifiable. The official troubleshooting instructions describe this configuration reset and restart sequence. OpenCode troubleshooting documentation
Do not edit several files and environment variables simultaneously. Save the original configuration, make one controlled change, fully quit Desktop, and then relaunch. Otherwise a successful connection will not tell you which setting fixed it, and restoring the old configuration may reintroduce the failure without an obvious cause.
3. Check the OPENCODE_PORT environment variable
Desktop uses OPENCODE_PORT for its local server. An inherited value can point Desktop at a port that is already occupied, blocked, or unsuitable for the current setup.
- Inspect the environment of the account launching Desktop.
- If
OPENCODE_PORTis set, temporarily remove it and relaunch Desktop. - If you need a fixed port, choose one that is free and consistent with the client URL, then restart the application.
- After changing the variable, fully quit and reopen Desktop; changing an environment value while the process is running does not change the existing server.
A port value is only useful when every part of the setup agrees. If the server listens on one port but the picker still contains another, Desktop will continue to report a connection failure. Treat an environment change as incomplete until the process has been restarted and the saved URL has been checked.
If clearing the server picker, removing the server section, and unsetting the variable all produce the same result, the failure is less likely to be a stale Desktop setting. Move on to checking whether the server process actually starts and whether another security or system component is blocking it.
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4. Interpret the result instead of changing several values at once
| Result after the test | Most useful next action |
|---|---|
| Desktop connects after Clear | Verify the old URL and save only the confirmed endpoint. |
Desktop connects after removing server |
Restore the configuration gradually and inspect server.port and server.hostname. |
Desktop connects after changing OPENCODE_PORT |
Keep a free, deliberate port and ensure any configured URL uses that port. |
| No change after all three tests | Determine whether Desktop’s interface is launching, whether a local server is listening, and whether the issue is actually a provider request rather than server connectivity. |
If the splash screen never becomes interactive, record whether a server process appears at all. That observation separates a Desktop launch problem from a client that started successfully but cannot reach its endpoint. Avoid assuming that a blank or frozen window proves the server is down.
The web page does not open or cannot reach the local service
Start the web server and use its printed URL
- Open a terminal on the machine where OpenCode should run.
- Run
opencode web. - Copy the complete URL printed by OpenCode into the browser on that same machine.
By default, the web service binds to 127.0.0.1 and selects a random available port. Do not guess the port or reuse an old browser bookmark; the terminal output is the authoritative address for that launch. The web command and default binding are documented at OpenCode Web.
Keep the terminal session running while testing. The browser depends on the service process launched by that command; closing the terminal or stopping the process ends that particular server instance. If you launch the command again, it may select a different available port, so copy the newly printed URL rather than relying on the previous one.
Use a predictable port when a random port is inconvenient
To request port 4096, run:
opencode web --port 4096Then open the URL for the host and port shown by the command. A fixed port helps when you are configuring a shortcut, reverse proxy, firewall rule, or Desktop server entry, but it can fail if another process already owns that port. If startup reports a port conflict, stop the conflicting process or choose another free port.
A predictable port does not change the binding scope. With the default localhost binding, port 4096 is still available only from the same machine. Decide separately whether the hostname should remain local or be changed for another device.
Allow access from another device only when necessary
127.0.0.1 accepts connections only from the same machine. To make the service reachable over a network, bind it to a reachable hostname such as 0.0.0.0. This changes the exposure of the service, so set OPENCODE_SERVER_PASSWORD before starting it and use the password when prompted or required by the client.
Binding to 0.0.0.0 does not mean that every address can automatically reach the service: operating-system firewalls, router isolation, containers, and virtual-machine networking can still block traffic. It does mean the process is no longer limited to loopback, so avoid doing it on an untrusted network. The documented web-server options and password guidance are available in OpenCode Web and OpenCode Server.
Do these 3 things before closing this tab:
1Repair Windows errors before they cause bigger problems2Fix the driver behind crashes, sound loss and screen glitches3Clear out junk files and repair common Windows errorsWhen testing from another device, use the host machine’s reachable address and the exact listening port. Opening 127.0.0.1 on the second device points to that second device, not to the computer running OpenCode. If local testing works but remote testing does not, investigate the hostname binding and network path before changing Desktop settings.
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Check CORS only for a custom frontend on another origin
If a custom web frontend is hosted at a different origin, the browser may reject requests even though the OpenCode server is running and reachable. In that case, configure the allowed origin with the server’s --cors option as described in the OpenCode Server documentation.
CORS is not the first fix for Desktop showing a wrong server URL. First confirm the URL, hostname, port, and server process. Add a CORS origin only when the browser developer tools or the frontend’s architecture indicate a cross-origin request is the actual failure.
Desktop connected to an OpenCode server in WSL
Start the server inside WSL
From the WSL terminal, run the documented server command:
opencode serve --hostname 0.0.0.0 --port 4096This listens on port 4096 and permits access through the WSL network interface. Because the hostname is broader than localhost, set OPENCODE_SERVER_PASSWORD as recommended by the Windows/WSL guidance.
Leave this WSL process running while Desktop connects. If the command exits, Desktop has no server to reach even if the URL remains correctly formatted. If you change the port, reflect the same change in the Desktop URL; if you restart WSL, be prepared to verify whether its address has changed.
Connect Desktop through localhost first
- Open OpenCode Desktop’s Server picker.
- Enter
http://localhost:4096as the server URL. - Save the selection and test the connection.
On many Windows and WSL configurations, localhost forwarding makes this work without exposing the WSL address directly. If Desktop cannot reach it, do not keep changing unrelated settings; test the WSL address next.
Use the WSL IP when localhost forwarding fails
- In WSL, run
hostname -I. - Use the relevant address in Desktop, formatted as
http://<wsl-ip>:4096. - Confirm that the WSL server is still running and that the port matches the URL.
The WSL address can change after a restart, so a previously saved URL may become stale. If the address changes, update Desktop’s server selection or return to localhost forwarding if it becomes available. The official Windows/WSL instructions cover both connection forms and recommend running opencode web from the WSL terminal for browser access. OpenCode Windows and WSL guide
For browser use, run opencode web from the WSL terminal and use the URL it prints. This is separate from entering the WSL server URL in Desktop: one command serves the browser interface, while opencode serve provides the server endpoint that Desktop can select.
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Set a password before exposing the server
When a server binds beyond localhost—such as with --hostname 0.0.0.0—set the OPENCODE_SERVER_PASSWORD environment variable before launching it. This applies to a WSL server and to a web server intended for another device.
- Set the variable in the same environment that starts
opencode serveoropencode web. - Restart the server after setting or changing it.
- Use the matching server URL and password in the connecting client.
- Remove the broad hostname binding when remote access is no longer needed.
A password does not repair a wrong port or an unreachable host. Treat authentication and transport as separate checks: first verify that the client can reach the address, then verify that credentials are accepted. If the service is reachable but rejects requests, confirm that the password belongs to the currently running process rather than an older terminal session.
When the problem is not server connectivity
Desktop is blank or will not launch
A blank window can be a UI-runtime problem rather than a failed server connection. On Windows, verify that the WebView2 Runtime required by Desktop is installed. On macOS, the official troubleshooting guidance suggests using Reload Webview for a blank or frozen interface.
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The app opens, but a provider request fails
If Desktop or Web loads and you can interact with the interface, the OpenCode server connection is already working. A failed model or provider request is a different layer. Use the following checks:
- Run OpenCode with
--print-logsand inspect the error produced when the request fails. - Bring the installation up to date with
opencode upgrade. - Verify provider authentication and API credentials.
- Use
/connectin OpenCode to authenticate again when the provider requires reauthorization.
These steps address provider/API failures, not a Desktop URL, WSL address, or web-port problem. The same troubleshooting page documents the logging, upgrade, and reauthentication checks. OpenCode troubleshooting documentation
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Common mistakes that make diagnosis slower
- Using an old bookmark:
opencode webnormally chooses a random free port, so the address can change between launches. - Opening localhost from the wrong computer: loopback always refers to the device where the browser is running.
- Forgetting to restart: Desktop and server processes keep their original environment and configuration until relaunched.
- Changing the port but not the URL: the client and server must use the same port.
- Exposing a service without a password: a non-local binding should be paired with
OPENCODE_SERVER_PASSWORD. - Blaming CORS too early: CORS matters for a custom frontend on another origin, not for a Desktop picker containing the wrong endpoint.
- Confusing UI and provider errors with transport errors: WebView2, a frozen webview, plugins, cache, credentials, and API limits belong to later diagnostic layers.
A shortest-path recovery sequence
Use this order when you need a fast, controlled diagnosis:
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opencode web. - For Desktop, open the Server picker and click Clear under Default server.
- If it still fails, temporarily remove the
serversection fromopencode.jsonoropencode.jsonc, then restart. - Check and unset or change
OPENCODE_PORT, then relaunch. - For Web, run
opencode weband open the exact printed URL; use--port 4096only when you need a fixed port. - For WSL, run the documented
opencode serve --hostname 0.0.0.0 --port 4096command, tryhttp://localhost:4096, and then the address fromhostname -Iif necessary. - Set
OPENCODE_SERVER_PASSWORDwhenever the service is reachable beyond localhost. - Only after the interface connects should you investigate WebView2, Reload Webview, plugins, cache, provider credentials, logs, or upgrades.
This sequence changes one connection variable at a time, making it clear whether the failure is a saved endpoint, server configuration, port, network binding, authentication, UI runtime, or provider layer.
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Frequently Asked Questions
Why does OpenCode Desktop say “Connection Failed” when the server is running?
Desktop may still be using a stale saved URL, an invalid server.port or server.hostname, or an unsuitable OPENCODE_PORT. Clear the Default server selection, temporarily remove the server section, and relaunch after checking the environment variable.
What URL should I open after running opencode web?
Use the complete URL printed in the terminal. Web binds to 127.0.0.1 by default and normally chooses a random available port, so an old bookmark may point to the wrong endpoint.
How do I make the web port predictable?
Run opencode web --port 4096, then use the host and port shown by the command. Choose another free port if 4096 is already occupied.
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Can Desktop connect to an OpenCode server running in WSL?
Yes. Run opencode serve --hostname 0.0.0.0 --port 4096 in WSL and try http://localhost:4096 in the Desktop Server picker. If localhost forwarding fails, run hostname -I and use http://<wsl-ip>:4096.
When is OPENCODE_SERVER_PASSWORD required?
Set it whenever the server is bound beyond localhost, such as with --hostname 0.0.0.0. A password protects access but does not fix a wrong host, port, or stopped server.
Is CORS the fix for a Desktop connection failure?
Usually not. CORS applies when a custom frontend on another origin calls the server. First verify the Desktop URL, hostname, port, and running server; configure --cors only when the frontend is genuinely cross-origin.
What if OpenCode opens but model requests fail?
That indicates a provider or API layer problem rather than server connectivity. Run with --print-logs, run opencode upgrade, verify provider credentials, and use /connect to reauthenticate when needed.
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What if Desktop is blank instead of showing a connection error?
Treat it first as a UI launch problem. On Windows, check the WebView2 Runtime. On macOS, try Reload Webview. Plugins and cached Desktop data are broader follow-up checks after server URL and port diagnostics.
The Bottom Line
Start with the connection path, not provider settings: clear Desktop’s saved server, temporarily remove server configuration, and check OPENCODE_PORT. For Web, use the exact URL printed by opencode web; for WSL, try localhost and then the address from hostname -I. Bind beyond localhost only when needed, and set OPENCODE_SERVER_PASSWORD whenever you do. Once the interface connects, investigate WebView2, webview state, plugins, logs, upgrades, and provider authentication as separate issues.
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