Error category
Troubleshoot Claude API request failures, SDK exceptions, rate limits, overload responses, Bedrock routing problems, tool-use errors, and prompt caching issues.
This Anthropic API troubleshooting hub collects real error signatures, quick fixes, common causes, and step-by-step debugging paths for developers who need a practical answer instead of a broad overview.
172 crawlable articles in this category. 105 additional records are indexed in JSON only (no standalone HTML route).
Browse Anthropic API records in the data catalog — search JSON index entries, including data-only records without standalone HTML guides.
Start by matching the exact error message, then check the technology, environment, credentials, network path, and deployment context. The pages below are grouped so you can move from broad Anthropic API symptoms to specific root-cause families without relying on client-side search.
Evidence labels are derived at build time from each Markdown record. Source-backed entries have public URLs under a Sources checked section, while partial-source entries expose public links without a complete source block.
These entries include public source URLs in the imported page body. Use them first when you need evidence for provider behavior, SDK regressions, or version-specific failures.
Fix recurring elevated error rates on Claude Opus 4.7 — model frequently returns errors despite being the premium tier Includes evidence for Anthropic API troubleshooting demand.
Elevated errors on Claude Opus 4.7 model requests Distinguish Anthropic HTTP 529 overloaded_error (server capacity saturation) from 429 rate limit errors; implement correct retry strategy for each Includes evidence for Anthropic API troubleshooting demand.
anthropic.APIStatusError: status_code=529, anthropic.error.overloaded_error: The API is temporarily overloaded. Fix Anthropic API 529 overloaded errors during peak traffic or model launches; implement retry-and-fallback strategy for production apps Includes evidence for Anthropic API troubleshooting demand.
HTTP 529 overloaded_error: "API Error: 529 overloaded" — global capacity saturation, not per-key rate limit Understand the difference between Anthropic 529 overloaded_error and 429 rate_limit_error to apply correct retry strategy (exponential backoff vs waiting for rate limit reset) Includes evidence for Anthropic API troubleshooting demand.
529 overloaded_error: The API is temporarily overloaded — frequently conflated with 429 rate_limit_error by developers Fix frequent 529 overloaded errors blocking Max plan Claude Code users, especially Opus model requests Includes evidence for Anthropic API troubleshooting demand.
529 Overloaded error during regular usage on Max subscriber plan Fix repeated 529 overloaded_error from Anthropic API causing Claude Code sessions to fail with escalating retries Includes evidence for Anthropic API / Claude Code troubleshooting demand.
API Error (529): overloaded_error — Repeated API Error (529 "type":"overloaded_error") responses during Claude Code terminal usage Fix permanently broken Anthropic conversation when extended thinking block signature is rejected by API after N turns Includes evidence for Anthropic API troubleshooting demand.
messages.X.content.Y: Invalid `signature` in `thinking` block Resolve 400 error caused by invalid thinking block signatures when resuming conversations, affecting streaming chat and function calling workflows Includes evidence for Anthropic API troubleshooting demand.
API returns 400 'Invalid signature in thinking block' when replaying conversation history with no recovery path Fix Anthropic API 429 OverloadedError caused by high traffic, implement retry/backoff strategy to continue API usage on paid plans Includes evidence for Anthropic API troubleshooting demand.
overloaded_error: Your API request is overloaded User encounters Anthropic API 500 internal server error when using Claude Code desktop app; needs to understand if this is transient or requires action. Includes evidence for Anthropic API / Claude Code troubleshooting demand.
API Error: 500 status code (no body). NON-FATAL: Lock acquisition failed for /Users/.../.local/share/claude/versions/ Fix missing error type mapping so Bedrock/Vertex users get specific typed exceptions (413→RequestTooLargeError, 529→OverloadedError) matching canonical Anthropic client behavior Includes evidence for Anthropic API troubleshooting demand.
Bedrock and Vertex client _make_status_error missing 413/529 status codes — returns generic APIStatusError instead of RequestTooLargeError / OverloadedError Understand and fix unexpected token billing overcharge caused by prompt caching extending beyond configured cache_control breakpoint, wasting money on cached-but-unread tokens Includes evidence for Anthropic API troubleshooting demand.
Server writes additional cache entries past explicit cache_control breakpoint, billing 1.25x for tokens that are never read by downstream models Handle Anthropic mid-stream SSE overloaded_error gracefully; prevent raw JSON leak to end-user UI; add proper error classification and retry logic Includes evidence for Anthropic API troubleshooting demand.
SSE event type 'overloaded_error' from Anthropic API surfaces raw JSON blob '{"type":"error","error":{"type":"overloaded_error",...}}' in Copilot chat bubble instead of user-safe error message Fix MCP SDK OAuth authorization error codes missing 'invalid_target' (RFC 8707), causing pydantic validation error instead of correct OAuth response Includes evidence for Anthropic API troubleshooting demand.
pydantic_core._pydantic_core.ValidationError: AuthorizationErrorResponse error Input should be 'invalid_request', 'unauthorized_client', 'access_denied', 'unsupported_response_type', 'invalid_scope', 'server_error' or 'temporarily_unavailable' Fix Anthropic API web_search tool getting stuck in internal loop, returning pause_turn without usable output, causing 55%+ failure rate in batch processing Includes evidence for Anthropic API troubleshooting demand.
web_search_20250209 dynamic filtering causes excessive pause_turn at ~110 content blocks — batch processing impractical Fix infinite loop in Anthropic SDK tool runner when calling append_messages() inside the loop iteration — tool results never reach history causing model to re-call same tool Includes evidence for Anthropic API troubleshooting demand.
[Bug] append_messages() inside tool runner loop causes infinite loop (advanced usage docs example) Fix subagent dispatch pattern where coordinator agent's vault-based OAuth credentials cannot reach subagent's MCP tool execution context Includes evidence for Anthropic API troubleshooting demand.
MCP OAuth calls fail in subagents — vault_ids parameter exists only on sessions.create, no mechanism to pass credentials when dispatching subagents via agent_toolset Fix anthropic SDK client.copy() method that propagates parent api_key into child clients, preventing credential provider (OAuth, GCP, AWS) authentication from working Includes evidence for Anthropic API troubleshooting demand.
copy(credentials=...) carries over inherited api_key even when replacing with credentials provider; AccessTokenAuth short-circuits Fix Bedrock streaming crash when API returns error SSE frames (rate_limit_error, overloaded_error) — should raise typed APIStatusError instead of AttributeError Includes evidence for Anthropic API troubleshooting demand.
AttributeError: 'NoneType' object has no attribute 'model' — Bedrock error payload routed as completion event in streaming Debug why Anthropic SDK with MCP beta returns plain tool_use instead of expected mcp_tool_use, causing agent loops to hang Includes evidence for Anthropic API troubleshooting demand.
MCP connector model intermittently emits tool_use instead of mcp_tool_use for tools declared in mcp_toolset — conversation stalls on client side Continue through the full static archive for this hub. Every listed page is crawlable and keeps its existing canonical URL.