Claude Code / AI Coding Tools
Claude Code Custom MCP Connector OAuth Tokens Fail to Persist
Developer configures custom MCP connector in Claude Code via claude.json, OAuth authentication succeeds initially but tokens fail to persist across sessions causing SDK auth failures Includes evidence for Claude Code troubleshooting demand.
- Category
- AI Coding Tools
- Error signature
Error: SDK auth failed- Quick fix
- Verify the account session, API key, provider settings, and environment where the failing tool is running.
- Updated
What this error means
Error: SDK auth failed is a Claude Code failure pattern reported for developers trying to developer configures custom mcp connector in claude code via claude.json, oauth authentication succeeds initially but tokens fail to persist across sessions causing sdk auth failures. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.
Why this happens
Found on GitHub claude-code repository issues (#52565). Specific to Claude Code MCP configuration with OAuth token persistence bug. Affects developers integrating external tools via MCP in Claude Code terminal IDE. Category: AI Coding Tools per mapping rules.
Common causes
- Found on GitHub claude-code repository issues (#52565). Specific to Claude Code MCP configuration with OAuth token persistence bug. Affects developers integrating external tools via MCP in Claude Code terminal IDE. Category: AI Coding Tools per mapping rules.
Quick fixes
- Confirm the exact error signature matches
Error: SDK auth failed. - Check the Claude Code account, local tool state, and provider configuration involved in the failing workflow.
- 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
- Capture the exact error message and the command, editor action, or request that triggered it.
- Check whether the failure is account/auth, quota/rate, model/provider, local runtime, or deployment configuration.
- Review the source evidence below and compare it with your environment.
- Apply one change at a time and rerun the smallest failing action.
- 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.
Sources checked
Evidence note: Found on GitHub claude-code repository issues (#52565). Specific to Claude Code MCP configuration with OAuth token persistence bug. Affects developers integrating external tools via MCP in Claude Code terminal IDE. Category: AI Coding Tools per mapping rules.
Related errors
- AI Coding Tools
FAQ
What should I check first?
Start with the exact Error: SDK auth failed text and the smallest action that reproduces it.
Can I ignore this error?
No. Treat it as a failed Claude Code workflow until the root cause is understood.
Is this guaranteed to have one fix?
No. The imported evidence supports the troubleshooting path above, but tool behavior can vary by account, plan, version, provider, and local configuration.
How do I know the fix worked?
Rerun the same command, editor action, or request. The fix is working when that action completes without Error: SDK auth failed.