Claude Code / AI Coding Tools

Claude Code OAuth Reconnection Fails After Successful Auth — MCP Streamable-HTTP Transport Bug

Fix MCP server reconnection failure after OAuth authentication succeeds in Claude Code using streamable-http transport Includes evidence for Claude Code troubleshooting demand.

Source-backed Last updated May 22, 2026 3 sources Needs local verification

Category: AI Coding Tools
Error signature: Authentication successful, but server reconnection failed
Quick fix: Verify the account session, API key, provider settings, and environment where the failing tool is running.
Updated: May 22, 2026
Verification status: Source-backed
Evidence: 3 public source URLs

Before you change production

This page includes public source URLs in the imported troubleshooting record. Compare those references with your version and environment before applying changes.

Reproduce the smallest failing action and save non-secret logs before changing configuration.
Check versions for Claude Code, related SDKs, package managers, CI runners, and hosting providers.
Change one setting or dependency at a time, then rerun the same failing command or request.
Avoid destructive commands, credential rotation, billing changes, or security relaxations without a rollback plan.

What this error means

Authentication successful, but server reconnection failed is a Claude Code failure pattern reported for developers trying to fix mcp server reconnection failure after oauth authentication succeeds in claude code using streamable-http transport. 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 anthropics/claude-code#10250 (browser CDP fetch). OAuth auth passes green but subsequent MCP server reconnection fails, requiring full Claude Code restart. Also corroborated by codersera.com 2026 troubleshooting guide covering Claude Code 529/401/MCP errors. Category maps to AI Coding Tools per approved list. High commercial value: blocks paid developers from using Claude Code mid-session.

Common causes

Found on GitHub anthropics/claude-code#10250 (browser CDP fetch). OAuth auth passes green but subsequent MCP server reconnection fails, requiring full Claude Code restart. Also corroborated by codersera.com 2026 troubleshooting guide covering Claude Code 529/401/MCP errors. Category maps to AI Coding Tools per approved list. High commercial value: blocks paid developers from using Claude Code mid-session.

Quick fixes

Confirm the exact error signature matches Authentication successful, but server reconnection 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.

Diagnostic flow for this page

Match Authentication successful, but server reconnection failed exactly before applying the quick fix.
Compare the failing environment with Claude Code versions, account scope, provider settings, and deployment context.
Check the listed common causes in order, starting with the cause that best matches your logs.
Use the evidence status below to decide whether to confirm against public sources or official documentation.
Apply one reversible change, rerun the smallest failing action, and keep rollback notes.

FAQ

What does Authentication successful, but server reconnection failed mean in Claude Code?

Authentication successful, but server reconnection failed indicates the workflow described by "Claude Code OAuth Reconnection Fails After Successful Auth — MCP Streamable-HTTP Transport Bug" failed in a AI Coding Tools context. Start by confirming the exact signature and the component that emitted it.

What should I check first for Authentication successful, but server reconnection failed?

Check whether this cause matches your environment: Found on GitHub anthropics/claude-code#10250 (browser CDP fetch). OAuth auth passes green but subsequent MCP server reconnection fails, requiring full Claude Code restart. Also corroborated by codersera.com 2026 troubleshooting guide covering Claude Code 529/401/MCP errors. Category maps to AI Coding Tools per approved list. High commercial value: blocks paid developers from using Claude Code mid-session.

Is the Authentication successful, but server reconnection failed guidance source-backed?

The "Claude Code OAuth Reconnection Fails After Successful Auth — MCP Streamable-HTTP Transport Bug" page is labeled source-backed. It has 3 public source URLs from github.com, codersera.com, truefoundry.com, so use that evidence status when deciding how much additional verification you need.

When should I avoid the quick fix for Authentication successful, but server reconnection failed?

For "Claude Code OAuth Reconnection Fails After Successful Auth — MCP Streamable-HTTP Transport Bug", avoid applying "Verify the account session, API key, provider settings, and environment where the failing tool is running." when the error text differs, the affected version or provider is different, or the change would touch credentials, billing, DNS, production deploy settings, or irreversible data.

What should I collect before debugging Authentication successful, but server reconnection failed?

For "Claude Code OAuth Reconnection Fails After Successful Auth — MCP Streamable-HTTP Transport Bug", collect the failing Claude Code command or request, non-secret configuration, versions, timestamps, request IDs when available, and the smallest reproduction that still triggers the signature.