Anthropic API / Anthropic API

Anthropic API Prompt Caching Writes Extra Cache Entries Billing 1.25x for Unread Tokens

Fix unexpected cache write charges on Anthropic API when using explicit cache_control breakpoint Includes evidence for Anthropic API troubleshooting demand.

Source-backed Last updated May 16, 2026 1 source Needs local verification

Category: Anthropic API
Error signature: cache_creation=1416 cache_read=2227 uncached_input=8 — server writes additional cache entries past explicit cache_control breakpoint
Quick fix: Compare the failing environment with a known working setup, then change one configuration value at a time.
Updated: May 16, 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 Anthropic API, 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

cache_creation=1416 cache_read=2227 uncached_input=8 — server writes additional cache entries past explicit cache_control breakpoint is a Anthropic API failure pattern reported for developers trying to fix unexpected cache write charges on anthropic api when using explicit cache_control breakpoint. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

GitHub issue #1547 on anthropic-sdk-python: server writes additional cache entry inside user content on warm calls despite only one explicit cache_control marker. Billed at 1.25x for tokens never read back. Reproducible on SDK 0.102.0 and 0.79.0, confirming server-side behavior. Direct billing impact for paying Anthropic API users.

Common causes

GitHub issue #1547 on anthropic-sdk-python: server writes additional cache entry inside user content on warm calls despite only one explicit cache_control marker. Billed at 1.25x for tokens never read back. Reproducible on SDK 0.102.0 and 0.79.0, confirming server-side behavior. Direct billing impact for paying Anthropic API users.

Quick fixes

Confirm the exact error signature matches cache_creation=1416 cache_read=2227 uncached_input=8 — server writes additional cache entries past explicit cache_control breakpoint.
Check the Anthropic API 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 cache_creation=1416 cache_read=2227 uncached_input=8 — server writes additional cache entries past explicit cache_control breakpoint exactly before applying the quick fix.
Compare the failing environment with Anthropic API 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 cache_creation=1416 cache_read=2227 uncached_input=8 — server writes additional cache entries past explicit cache_control breakpoint mean in Anthropic API?

cache_creation=1416 cache_read=2227 uncached_input=8 — server writes additional cache entries past explicit cache_control breakpoint indicates the workflow described by "Anthropic API Prompt Caching Writes Extra Cache Entries Billing 1.25x for Unread Tokens" failed in a Anthropic API context. Start by confirming the exact signature and the component that emitted it.

What should I check first for cache_creation=1416 cache_read=2227 uncached_input=8 — server writes additional cache entries past explicit cache_control breakpoint?

Check whether this cause matches your environment: GitHub issue #1547 on anthropic-sdk-python: server writes additional cache entry inside user content on warm calls despite only one explicit cache_control marker. Billed at 1.25x for tokens never read back. Reproducible on SDK 0.102.0 and 0.79.0, confirming server-side behavior. Direct billing impact for paying Anthropic API users.

Is the cache_creation=1416 cache_read=2227 uncached_input=8 — server writes additional cache entries past explicit cache_control breakpoint guidance source-backed?

The "Anthropic API Prompt Caching Writes Extra Cache Entries Billing 1.25x for Unread Tokens" 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 cache_creation=1416 cache_read=2227 uncached_input=8 — server writes additional cache entries past explicit cache_control breakpoint?

For "Anthropic API Prompt Caching Writes Extra Cache Entries Billing 1.25x for Unread Tokens", 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 cache_creation=1416 cache_read=2227 uncached_input=8 — server writes additional cache entries past explicit cache_control breakpoint?

For "Anthropic API Prompt Caching Writes Extra Cache Entries Billing 1.25x for Unread Tokens", collect the failing Anthropic API command or request, non-secret configuration, versions, timestamps, request IDs when available, and the smallest reproduction that still triggers the signature.