Windows: managed service fails when default port 49374 is in an excluded TCP range #53351

Description

On Windows, OpenCode Desktop 2.0.23 can fail to start its managed local service when the default service port 49374 falls inside a Windows TCP excluded port range.

On the affected system, port 49374 was not owned by any process, but Windows had excluded the range 49292–49391, which contains 49374. OpenCode nevertheless reported:

Managed service port 49374 on 127.0.0.1 is already in use by another process.
Configure another port with `opencode service set port <port>` and start the service again.

The managed-service path also retries the same unusable port instead of automatically selecting another available port.

Steps to reproduce

1. Check the Windows excluded TCP ranges:

netsh interface ipv4 show excludedportrange protocol=tcp

2. On the affected system, 49292–49391 was excluded, so 49374 was inside the excluded range.

3. Confirm that no process is listening on 49374:

netstat -ano | Select-String "49374"
Get-NetTCPConnection -LocalPort 49374

Both returned no listener/owning process.

4. Start OpenCode Desktop 2.0.23. The managed service fails to start.

5. Reproduce directly with:

opencode serve --port 49374

This fails even though no process owns the port.

6. As a control, use another available port:

opencode serve --port 49400

The service successfully binds to 127.0.0.1:49400.

Expected behavior

If the configured/default managed-service port cannot be bound, OpenCode should automatically recover by selecting another usable port, or report that the port is unavailable/reserved rather than claiming that another process owns it.

The service should not repeatedly retry the same unusable port.

Actual behavior

The managed service attempts to bind 49374, fails, and reports that the port is already in use even though no process owns it.

The user must manually configure another port to recover.

Technical details

The default OpenCode service port is 49374 (0xc0de).

In managed-service mode, the explicitly resolved port bypasses the existing available-port scan/fallback path. The retry logic retries the same port instead of selecting another usable port.

The bind failure is also surfaced through the existing EADDRINUSE-based "already in use" classification, resulting in a misleading user-facing error when the port is actually unavailable for binding.

Scope

This appears to be a Windows-specific manifestation of the managed-service bind failure. The issue is in the CLI/service layer used by Desktop; Desktop launches the bundled CLI using the managed-service path and does not independently select the service port.

Related to existing OpenCode/Bun issues involving listen/bind failures being surfaced as EADDRINUSE, but this report specifically concerns the default managed-service port 49374 falling inside a Windows excluded TCP port range and the lack of automatic fallback for the managed-service path.

Plugins

None

OpenCode version

2.0.23

Steps to reproduce

1. On Windows, check the excluded TCP port ranges:
   netsh interface ipv4 show excludedportrange protocol=tcp
   On the affected system, 49292–49391 was excluded, which contains the default OpenCode service port 49374.

2. Confirm that no process owns port 49374:
   netstat -ano | Select-String "49374"
Get-NetTCPConnection -LocalPort 49374
   Both return no listener.

3. Start OpenCode Desktop 2.0.23. The managed service attempts to bind 127.0.0.1:49374 and fails with:
   Managed service port 49374 on 127.0.0.1 is already in use by another process.

4. Reproduce directly with the bundled/CLI service:
   opencode serve --port 49374
   This fails even though no process is listening on the port.

5. As a control, start the service on another available port such as 49400; it binds successfully and responds to /api/health.

Screenshot and/or share link

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Caused by:
{
"name": "UnknownError",
"message": "An error occurred in Effect.tryPromise",
"cause": {
"name": "Error",
"message": "Server process exited with code 1\nError: Managed service port 49374 on 127.0.0.1 is already in use by another process. Configure another port with opencode service set port <port> and start the service again.\n at (B:/~BUN/root/chunk-b3kxkarp.js:2:7950) {\n [cause]: ServeError: \n at G (B:/~BUN/root/chunk-k64283rx.js:54:51704)\n at applyHandlers (node:events:64:20)\n at emitError (node:events:44:27)\n at emitListenErrorNextTick (node:_http_server:134:12)\n at processTicksAndRejections (unknown:7:39) {\n [cause]: Error: Failed to start server. Is port 49374 in use?\n at serve (unknown)\n at (node:_http_server:359:39)\n at (node:_http_server:332:33)\n at (B:/~BUN/root/chunk-k64283rx.js:54:51742)\n }\n}"
}
}

Operating System

Windows 11

Terminal

Windows Terminal (PowerShell)