Jetbrains ACP Integration - Internal Server Error

[xolotlatoani]

Description

I am unable to use opencode through ACP in any Jetbrains IDE. When I check the logs I get:

[OpenCode] stderr: Error handling request {
  type: "com.agentclientprotocol.rpc.JsonRpcRequest",
  id: 2,
  method: "session/new",
  params: {
    cwd: "REPO_PATH",
    mcpServers: [],
  },
  jsonrpc: "2.0",
} {
  code: -32603,
  message: "Internal error",
  data: {},
}


2026-03-02 13:45:46,998 [ 483376]   INFO - #c.i.m.l.a.a.p.AcpProcessHandlerService - Stopping process handler for agent acp.registry.opencode in chat 3a9c6068-2815-4071-9543-21a15b894320
2026-03-02 13:45:46,998 [ 483376]   INFO - #c.i.m.l.a.a.p.EelAcpProcessHandler - [OpenCode] Stopping server
2026-03-02 13:45:46,998 [ 483376]   INFO - #c.i.m.l.a.a.p.AcpProcessHandlerService - Successfully stopped process handler for agent acp.registry.opencode in chat 3a9c6068-2815-4071-9543-21a15b894320
2026-03-02 13:45:46,998 [ 483376]   INFO - #c.i.m.l.a.a.c.AcpSessionLifecycleManager - Session cancelled for chat 3a9c6068-2815-4071-9543-21a15b894320
2026-03-02 13:45:46,998 [ 483376]   WARN - #c.i.m.l.a.a.c.AcpSessionLifecycleManager - Failed to initialize ACP session for chat 3a9c6068-2815-4071-9543-21a15b894320, error: com.agentclientprotocol.protocol.JsonRpcException: Internal error
2026-03-02 13:45:46,998 [ 483376]   INFO - #c.i.m.l.a.a.p.EelAcpProcessHandler - [OpenCode] Sending SIGTERM (graceful shutdown)...
2026-03-02 13:45:47,011 [ 483389]   INFO - #c.i.m.l.a.a.p.EelAcpProcessHandler - [OpenCode] Stderr stream closed
2026-03-02 13:45:47,011 [ 483389]   INFO - #c.i.m.l.a.a.p.EelAcpProcessHandler - [OpenCode] Cleaning up process resources
2026-03-02 13:45:47,011 [ 483389]   FINE - #c.i.m.l.a.a.p.AcpProcessHandlerService - No process handler found for agent acp.registry.opencode in chat 3a9c6068-2815-4071-9543-21a15b894320
2026-03-02 13:45:47,011 [ 483389]   WARN - #c.i.m.l.a.a.p.EelAcpProcessHandler - [OpenCode] Process terminated with exit code 143
2026-03-02 13:45:47,011 [ 483389]   INFO - #c.i.m.l.a.a.p.EelAcpProcessHandler - [OpenCode] Cleaning up process resources
2026-03-02 13:45:47,011 [ 483389]   INFO - #c.i.m.l.a.a.c.AcpSessionLifecycleManager - Session cancelled for chat 3a9c6068-2815-4071-9543-21a15b894320
2026-03-02 13:45:47,041 [ 483419]   INFO - #c.i.w.i.i.j.s.JpsGlobalModelSynchronizerImpl - Saving global entities com.intellij.platform.workspace.jps.entities.SdkEntity to files
2026-03-02 13:45:47,044 [ 483422]   INFO - #c.i.w.i.i.j.s.JpsGlobalModelSynchronizerImpl - Saving global entities com.intellij.platform.workspace.jps.entities.LibraryEntity to files
2026-03-02 13:45:47,105 [ 483483]   INFO - #c.i.m.l.c.a.CodexOAuthStateManager - getState() called, isAuthenticated=false
2026-03-02 13:45:53,928 [ 490306]   INFO - #c.i.w.i.i.j.s.JpsGlobalModelSynchronizerImpl - Saving global entities com.intellij.platform.workspace.jps.entities.SdkEntity to files
2026-03-02 13:45:53,931 [ 490309]   INFO - #c.i.w.i.i.j.s.JpsGlobalModelSynchronizerImpl - Saving global entities com.intellij.platform.workspace.jps.entities.LibraryEntity to files

Plugins

none

OpenCode version

1.2.15

Steps to reproduce

1. Be behind a corporate proxy and self-signed certificate
2. Install ACP Agent in IntelliJ
3. Open a new JetBrains AI session
4. Select Opencode as the agent
5. Receive error: Failed to initialize ACP session. Error: Internal error

Screenshot and/or share link

No response

Operating System

macOS 26.3

Terminal

No response

[xolotlatoani]

Upon review, the NoProxy flag in my cntlm configuration was missing the entry 127.0.0.1, despite including localhost and 0.0.0.0.

After updating my configuration, everything started working!