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No configuration upload AI coding agents · Local browser tool

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Narrow the troubleshooting library before changing configuration.

Codex26 fixes

Windows sandbox · WSL · config · VS Code

Claude Code7 fixes

MCP launch · Playwright · NPX · plugins

MCP5 fixes

Filesystem · paths · stdio · connections

Diagnostics

Check the configuration and environment behind an agent failure.

All diagnostics

MCP · Local browser tool

MCP Config Validator

Check MCP JSON configuration syntax and common command, args, env, npx, and Windows path risks locally in your browser.

Agent PATH Inspector

Inspect a copied Windows, WSL, macOS, or Linux PATH for duplicates, empty entries, quoting, delimiter, and mixed-namespace risks.

No configuration upload AI coding agents · Local browser tool

Windows Command Resolver

Compare pasted where.exe and PowerShell Get-Command results to find stale shims, duplicate installs, and executable precedence conflicts.

No configuration upload Codex · Local browser tool

Codex Error Log Parser

Match pasted Codex logs to known exact-error branches and source-linked troubleshooting pages without uploading the log.

No configuration upload Codex · Local browser tool

TOML Path Escape Checker

Check Codex config.toml snippets for unsafe Windows backslashes, mixed WSL paths, duplicate keys, and unexpanded placeholders.

No configuration upload

Latest fixes

Recently checked troubleshooting notes from the current library.

Claude CodeConfirmed workaround

Claude Code Playwright MCP fails after /c becomes C:/

Failed to reconnect to plugin:playwright:playwright

Windows setup didn't finish

Windows setup didn't finish: helper_failed

windows sandbox: helper_unknown_error: apply deny-read ACLs

Codex helper_unknown_error while applying deny-read ACLs

windows sandbox: runner error: CreateProcessAsUserW failed: 1312

CreateProcessAsUserW failed: 1312 in the Codex Windows sandbox

Error accessing directory ... ENOENT: no such file or directory, stat ...

MCPConfirmed workaround

MCP Filesystem disconnects when an allowed directory is missing

bwrap: Can't mkdir /mnt/c/Users/.claude: Permission denied

Claude CodeOpen issue

Claude Code WSL tries to create /mnt/c/Users/.claude

Access denied - path outside allowed directories: Y:\k8s not in \\server\share\git

MCPConfirmed workaround

MCP Filesystem rejects a mapped drive but allows its UNC path

windows sandbox: timed out after 15000ms waiting for runner spawn_ready

Codex times out waiting for runner spawn_ready

Claude CodePartial workaround

Claude Desktop passes a literal ${VAR} to an MCP server

MCP server receives the literal string ${VAR}

MCP startup failed: handshaking with MCP server failed: JSON-RPC error: -32603

Codex bundled MCP fails with JSON-RPC error -32603

SEC_E_NO_CREDENTIALS (0x8009030e)

Codex Windows sandbox fails HTTPS with SEC_E_NO_CREDENTIALS

Claude CodePartial workaround

Claude Code startup fails with ERR_SOCKET_CLOSED behind a proxy

Failed to connect to api.anthropic.com: ERR_SOCKET_CLOSED

Error: account/read failed during TUI bootstrap

account/read failed during TUI bootstrap

windows sandbox: CryptUnprotectData failed: 2148073483

Codex sandbox DPAPI error followed by setup error 0xc0000142

privileged native pipe bridge is not available; browser-client is not trusted

Codex Browser fails because browser-client is not trusted

bwrap: loopback: Failed RTM_NEWADDR: Operation not permitted

bwrap loopback Failed RTM_NEWADDR: Operation not permitted

Claude CodePartial workaround

Claude Desktop cancels MCP initialize after 60 seconds

Message from client: method="notifications/cancelled"

bwrap: Can't mkdir /tmp/codex-bwrap-synthetic-mount-targets-1000: Read-only file system

bwrap cannot create the Codex synthetic mount directory in /tmp

windows sandbox: runner error: CreateProcessAsUserW failed: 5

Codex Windows sandbox fails with CreateProcessAsUserW error 5

helper_firewall_policy_access_failed: CoCreateInstance NetFwPolicy2 failed: HRESULT(0x80110474)

CoCreateInstance NetFwPolicy2 failed in Codex sandbox setup

idle timeout waiting for SSE

idle timeout waiting for SSE hides response.failed

Project folder was deleted or moved

Codex rewrites a WSL /mnt project path to a Windows drive

failed to connect to app-server remote control websocket

Codex Remote Control WebSocket returns HTTP 503

Codex cannot access its local database

Codex Desktop SQLite pool times out during startup

configRequirements/read failed during TUI bootstrap

configRequirements/read fails with No file descriptors available

SSE stream disconnected: TypeError: terminated

MCPOpen issue

MCP SSE stream disconnects with TypeError: terminated

thread-store internal error: thread history projection ... expected ordinal 192591, got 192590 (code -32603)

thread history projection expected ordinal N, got N-1

StreamableHTTPError: Streamable HTTP error: Failed to open SSE stream: Not Found

MCPPartial workaround

MCP fails to open an SSE stream with Not Found

Codex app-server initialize handshake timed out

Codex app-server initialize handshake times out in WSL mode

Fatal Error: HW capability found: 0x178BFBFF 0x7EF8320B, but HW capability requested: 0x200000 0x00.

Codex fatal error: HW capability requested

side_channel_waiting_key_absent

Claude CodeOpen issue

Claude Desktop MCP tools fail with side_channel_waiting_key_absent

failed to reload config: missing escaped value, expected `b`, `e`, `f`, `n`, `r`, `\`, `"`, `x`, `u`, `U`

Codex config.toml missing escaped value on Windows

Claude CodeConfirmed workaround

Claude Code MCP spawn npx ENOENT on Windows

SPAWN ERROR: ENOENT spawn npx ENOENT

Unable to spawn codex-linux-sandbox because it doesn't exist on the filesystem (ENOENT: No such file or directory)

Codex Linux sandbox helper ENOENT in WSL

Error: Access denied - path outside allowed directories: c:\Users\... not in C:\Users\...

MCPPartial workaround

MCP Filesystem rejects a Windows drive-letter case mismatch