Claude Code / AI Coding Tools

Claude Code prompt-caching-scope Beta Header Error on Custom API Endpoints — Fix

Fix Claude Code sending prompt-caching-scope beta header to custom API endpoints that don't support it Includes evidence for Claude Code troubleshooting demand.

Source-backed Last updated May 12, 2026 1 source Needs local verification

Category: AI Coding Tools
Error signature: Unexpected value(s) prompt-caching-scope-2026-01-05 for the anthropic-beta header
Quick fix: Compare the failing environment with a known working setup, then change one configuration value at a time.
Updated: May 12, 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

Unexpected value(s) prompt-caching-scope-2026-01-05 for the anthropic-beta header is a Claude Code failure pattern reported for developers trying to fix claude code sending prompt-caching-scope beta header to custom api endpoints that don't support it. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

Claude Code extension v2.1.23 sends prompt-caching-scope-2026-01-05 beta header to custom API endpoints (via ANTHROPIC_BASE_URL) even when enablePromptCaching and useAnthropicBetaHeaders are both set to false. Results in API error on incompatible endpoints.

Common causes

When Claude Code is configured with ANTHROPIC_BASE_URL pointing to a custom endpoint (proxy, mock server, or alternative provider), it injects the prompt-caching-scope-2026-01-05 beta header even when prompt caching is disabled, causing 400 errors. Developers using custom API gateways encounter this incompatibility.
Claude Code extension v2.1.23 sends prompt-caching-scope-2026-01-05 beta header to custom API endpoints (via ANTHROPIC_BASE_URL) even when enablePromptCaching and useAnthropicBetaHeaders are both set to false. Results in API error on incompatible endpoints.

Quick fixes

Confirm the exact error signature matches Unexpected value(s) prompt-caching-scope-2026-01-05 for the anthropic-beta header.
Check the Claude Code account, local tool state, and provider configuration involved in the failing workflow.
Compare the failing environment with a known working setup, then change one configuration value at a time.

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 Unexpected value(s) prompt-caching-scope-2026-01-05 for the anthropic-beta header 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 Unexpected value(s) prompt-caching-scope-2026-01-05 for the anthropic-beta header mean in Claude Code?

Unexpected value(s) prompt-caching-scope-2026-01-05 for the anthropic-beta header indicates the workflow described by "Claude Code prompt-caching-scope Beta Header Error on Custom API Endpoints — Fix" 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 Unexpected value(s) prompt-caching-scope-2026-01-05 for the anthropic-beta header?

Check whether this cause matches your environment: When Claude Code is configured with ANTHROPIC_BASE_URL pointing to a custom endpoint (proxy, mock server, or alternative provider), it injects the prompt-caching-scope-2026-01-05 beta header even when prompt caching is disabled, causing 400 errors. Developers using custom API gateways encounter this incompatibility.

Is the Unexpected value(s) prompt-caching-scope-2026-01-05 for the anthropic-beta header guidance source-backed?

The "Claude Code prompt-caching-scope Beta Header Error on Custom API Endpoints — Fix" 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 Unexpected value(s) prompt-caching-scope-2026-01-05 for the anthropic-beta header?

For "Claude Code prompt-caching-scope Beta Header Error on Custom API Endpoints — Fix", avoid applying "Compare the failing environment with a known working setup, then change one configuration value at a time." 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 Unexpected value(s) prompt-caching-scope-2026-01-05 for the anthropic-beta header?

For "Claude Code prompt-caching-scope Beta Header Error on Custom API Endpoints — Fix", 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.