Claude.ai MCP Connector Authorization Failed After OAuth Completes

What this error means

Authorization with the MCP server failed is a Anthropic API failure pattern reported for developers trying to fix claude.ai mcp connector showing ‘authorization with the mcp server failed’ after oauth completes successfully. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

Open issue with 17 comments. OAuth flow completes (confirmed via Salesforce OAuth Usage), token issued and used, but claude.ai returns ‘Authorization with the MCP server failed’. Tested with GA setup: v1 endpoint, mcp_api scope, PKCE, OAuth Client ID in claude.ai Advanced settings. Issue persists identically across multiple attempts.

Common causes

• When connecting Salesforce Hosted MCP (or other custom MCP connectors) to claude.ai, OAuth completes successfully and tokens are issued, but claude.ai fails to complete the authenticated MCP handshake. The connector never shows as ‘Connected’. This affects enterprise developers setting up MCP integrations, a key use case for Claude.ai’s extensibility. Issue persists across both beta and GA endpoints with correct OAuth Client ID configuration.
• Open issue with 17 comments. OAuth flow completes (confirmed via Salesforce OAuth Usage), token issued and used, but claude.ai returns ‘Authorization with the MCP server failed’. Tested with GA setup: v1 endpoint, mcp_api scope, PKCE, OAuth Client ID in claude.ai Advanced settings. Issue persists identically across multiple attempts.

Quick fixes

1. Confirm the exact error signature matches Authorization with the MCP server failed.
2. Check the Anthropic API 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.

Sources checked

• https://github.com/anthropics/claude-ai-mcp/issues/171

Evidence note: Open issue with 17 comments. OAuth flow completes (confirmed via Salesforce OAuth Usage), token issued and used, but claude.ai returns ‘Authorization with the MCP server failed’. Tested with GA setup: v1 endpoint, mcp_api scope, PKCE, OAuth Client ID in claude.ai Advanced settings. Issue persists identically across multiple attempts.

Related errors

• Claude.ai MCP custom connector timeout
• MCP server OAuth token refresh failed
• claude.ai custom connector 403 forbidden

FAQ

What should I check first?

Start with the exact Authorization with the MCP server failed text and the smallest action that reproduces it.

Can I ignore this error?

No. Treat it as a failed Anthropic API 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 Authorization with the MCP server failed.