OpenAI Codex CLI error
Codex CLI: MCP client for playwright failed to start: program not found
MCP client for `playwright` failed to start: program not foundStatus: Fixed in releaseLast verified 3 documented fixes5 sources
What it means
Codex could not find the executable named in the MCP server's command, so the server never started.
Causes
- Per PR #3828: on Windows, tools like npx, pnpm and yarn are .cmd/.bat scripts rather than .exe binaries, and Rust's std::process::Command bypasses the shell, so it cannot execute them without PATHEXT resolution.
- Per PR #5579: on Windows, MCP child processes missed core environment variables.
How to fix it
- Fix 1.
Upgrade to 0.59.0 or later: PR #3828 resolves MCP commands through PATH/PATHEXT on Windows (closes #2945).
- Fix 2.
Before that fix, the PR notes Windows users had to specify full paths or add .cmd extensions manually in config.toml.
- Fix 3.
PR #5579 (0.51.0) makes Windows MCP child processes inherit common core variables and mirror PATH to Path, so typical CLIs work without per-server env blocks.
More Codex CLI errors
All 14 Codex CLI errorsstream disconnected before completion: stream closed before response.completedStatus: Workaroundstream disconnected before completion: error sending request for url (https://chatgpt.com/backend-api/codex/responses)Status: OpenError running remote compact task: stream disconnected before completion: error sending request for url (https://chatgpt.com/backend-api/codex/responses/compact)Status: Fixed in releaseSelected model is at capacity. Please try a different model.Status: By designYour access token could not be refreshed because your refresh token was already used. Please log out and sign in again.Status: Fixed in releaseCodex ran out of room in the model's context window. Start a new thread or clear earlier history before retrying.Status: Fixed in releaseError logging in: Port 127.0.0.1:1455 is already in useStatus: WorkaroundToken exchange failed: token endpoint returned status 403 ForbiddenStatus: Workaround
Related reading
- Codex CLI Background Daemon: How to Turn It OffCodex CLI starts a persistent, self-updating background daemon since 0.157.0. What it does, why it hit Hacker News and the reported workaround to turn it off.
- How to Make Claude Code 10x Better at Design: Image and Video Assets From the Agent LoopMake Claude Code better at design by putting image and video generation in the agent loop with Higgsfield MCP and CLI, so sites ship with real assets.
- Codex and Claude Code in July 2026: Agent Controls Are the FeatureCodex and Claude Code July 2026 updates compared: why approval modes, resumable work, MCP auth, artifacts and review surfaces now matter as much as models.
- AgentCanvas is a visual adapter for Claude Code and CodexAgentCanvas is a visual adapter for Claude Code and Codex that puts artifacts, decisions and handoffs on one board, so the next agent or human can see them.
- GitHub Copilot Agent Finder: What ARD Means for Third-Party AI Tools in 2026GitHub Copilot Agent Finder discovers and invokes MCP servers, skills and agents like Claude and Codex. How the open ARD spec changes AI tool integration.
- AgentMemory Is Useful Only If You Audit What It RemembersAgentMemory gives Claude Code, Codex and Cursor persistent local memory. The real adoption test is whether your team can inspect, prune and govern it.
FAQ
What does "MCP client for playwright failed to start: program not found" mean in Codex CLI?
Codex could not find the executable named in the MCP server's command, so the server never started.
How do I fix "MCP client for playwright failed to start: program not found"?
There are 3 documented fixes. Start with the first: Upgrade to 0.59.0 or later: PR #3828 resolves MCP commands through PATH/PATHEXT on Windows (closes #2945).
Is this Codex CLI error fixed?
Status: Fixed in release. A release fixed this. The affected versions note says where the fix landed. Affected versions: Reported on codex-cli 0.25.0, Windows 11 (#2945); fixed in 0.59.0
Sources
Last verified against 5 sources: official docs, maintainer replies and release notes.
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