Claude Code / AI Coding Tools

[BUG] MCP OAuth complete_authentication always fails with No OAuth flow is in progress

Fix Claude Code MCP server OAuth flow where PKCE state is lost between authenticate and complete_authentication steps Includes evidence for Claude Code troubleshooting demand.

Source-backed Last updated May 20, 2026 1 source Needs local verification

Category: AI Coding Tools
Error signature: "No OAuth flow is in progress for {provider}. Call mcp__{provider}__authenticate first"
Quick fix: Verify the account session, API key, provider settings, and environment where the failing tool is running.
Updated: May 20, 2026
Verification status: Source-backed
Evidence: 1 public source URL

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

"No OAuth flow is in progress for {provider}. Call mcp__{provider}__authenticate first" is a Claude Code failure pattern reported for developers trying to fix claude code mcp server oauth flow where pkce state is lost between authenticate and complete_authentication steps. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

GitHub bug report on claude-code repo: HTTP-type MCP servers with OAuth lose in-memory PKCE state before complete_authentication can consume it. Configured .mcp.json with oauth causes auth flow to fail silently. This blocks all MCP-based integrations (Asana, Datadog, Slack etc.) for enterprise users. Mapping to AI Coding Tools: Claude Code is a paid AI coding IDE, MCP auth is integral to its workflow.

Common causes

GitHub bug report on claude-code repo: HTTP-type MCP servers with OAuth lose in-memory PKCE state before complete_authentication can consume it. Configured .mcp.json with oauth causes auth flow to fail silently. This blocks all MCP-based integrations (Asana, Datadog, Slack etc.) for enterprise users. Mapping to AI Coding Tools: Claude Code is a paid AI coding IDE, MCP auth is integral to its workflow.

Quick fixes

Confirm the exact error signature matches "No OAuth flow is in progress for {provider}. Call mcp__{provider}__authenticate first".
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 "No OAuth flow is in progress for {provider}. Call mcp__{provider}__authenticate first" 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 "No OAuth flow is in progress for {provider}. Call mcp{provider}authenticate first" mean in Claude Code?

"No OAuth flow is in progress for {provider}. Call mcp__{provider}__authenticate first" indicates the workflow described by "[BUG] MCP OAuth complete_authentication always fails with No OAuth flow is in progress" 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 "No OAuth flow is in progress for {provider}. Call mcp{provider}authenticate first"?

Check whether this cause matches your environment: GitHub bug report on claude-code repo: HTTP-type MCP servers with OAuth lose in-memory PKCE state before complete_authentication can consume it. Configured .mcp.json with oauth causes auth flow to fail silently. This blocks all MCP-based integrations (Asana, Datadog, Slack etc.) for enterprise users. Mapping to AI Coding Tools: Claude Code is a paid AI coding IDE, MCP auth is integral to its workflow.

Is the "No OAuth flow is in progress for {provider}. Call mcp{provider}authenticate first" guidance source-backed?

The "[BUG] MCP OAuth complete_authentication always fails with No OAuth flow is in progress" page is labeled source-backed. It has 1 public source URL from github.com, so use that evidence status when deciding how much additional verification you need.

When should I avoid the quick fix for "No OAuth flow is in progress for {provider}. Call mcp{provider}authenticate first"?

For "[BUG] MCP OAuth complete_authentication always fails with No OAuth flow is in progress", 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 "No OAuth flow is in progress for {provider}. Call mcp{provider}authenticate first"?

For "[BUG] MCP OAuth complete_authentication always fails with No OAuth flow is in progress", 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.