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authentication_error
Anthropic API Error authentication_error: Invalid x-api-key (401)
Critical✕ Not retryable · fix the payloadHTTP 401 UnauthorizedAI Provider
TL;DR · 10-second read
The API key is missing, revoked or sent in the wrong header. Anthropic expects it in x-api-key, not Authorization: Bearer.
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What you see · exact log / response
{"type":"error","error":{"type":"authentication_error","message":"invalid x-api-key"}}Fix
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Copy-paste fixes for authentication_error are in the enrichment queue
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Last verified 2026-10-22 · Source: Anthropic API error reference + SDK docs · Official docs ↗ · ~2,900 searches/mo