What this error means

OAuth error: listen EACCES: permission denied 0.0.0.0 is a Claude Code failure pattern reported for developers trying to fix claude code mcp oauth authorization failure caused by localhost listener port conflict or firewall blocking the oauth redirect callback on 0.0.0.0. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

GitHub claude-code issue #1841 reports EACCES error preventing OAuth flow completion. AI overview reveals multiple root causes: DCR incompatibility with some MCP servers, insufficient scopes requiring step-up auth, and network/WAF interference. Atlassian Community also reports Authorization with MCP server failed. High value: affects developers integrating enterprise tools with Claude Code daily workflow.

Common causes

  • GitHub claude-code issue #1841 reports EACCES error preventing OAuth flow completion. AI overview reveals multiple root causes: DCR incompatibility with some MCP servers, insufficient scopes requiring step-up auth, and network/WAF interference. Atlassian Community also reports Authorization with MCP server failed. High value: affects developers integrating enterprise tools with Claude Code daily workflow.

Quick fixes

  1. Confirm the exact error signature matches OAuth error: listen EACCES: permission denied 0.0.0.0.
  2. Check the Claude Code account, local tool state, and provider configuration involved in the failing workflow.
  3. Verify the account session, API key, provider settings, and environment where the failing tool is running.

Platform/tool-specific checks

  • Verify the command, editor, extension, or API client that produced the error.
  • Compare local settings with CI, deployment, or editor-level settings when the error appears in only one environment.
  • Avoid deleting credentials, local model data, or project settings until the failing scope is clear.

Step-by-step troubleshooting

  1. Capture the exact error message and the command, editor action, or request that triggered it.
  2. Check whether the failure is account/auth, quota/rate, model/provider, local runtime, or deployment configuration.
  3. Review the source evidence below and compare it with your environment.
  4. Apply one change at a time and rerun the smallest failing action.
  5. Keep the working fix documented for the team or deployment environment.

How to prevent it

  • Keep provider/tool configuration documented.
  • Record non-secret diagnostics such as tool version, provider name, model name, and command path.
  • Add a lightweight check before CI or production workflows depend on the tool.