Short answer: 413 means the payload your endpoint receives is too large for it to accept. ElevenLabs does not document a 413 webhook error or a 262,144‑byte limit on their side.
What ElevenLabs does document
Post‑call transcription webhooks include the full conversation transcript, analysis results, and metadata. These bodies can be large. Ensure your endpoint can accept and parse them, then return HTTP 200 quickly. (elevenlabs.io)
Post‑call audio webhooks are delivered separately, can be toggled on/off with “Send audio data,” and are sent using Transfer‑Encoding: chunked to handle large audio efficiently. If you enable audio webhooks, your server must handle streaming bodies. (elevenlabs.io)
Webhooks that repeatedly fail are auto‑disabled after 10 consecutive failures when the last success was >7 days ago; failed webhooks aren’t retried for HIPAA reasons. (elevenlabs.io)
You can treat the webhook as a trigger and fetch conversation details (including transcript) via the Conversations API instead of relying on a very large webhook payload. (elevenlabs.io)
ElevenLabs’ published error-messages page covers 400/401/403/429 but does not list 413. (elevenlabs.io)
How to resolve
Increase the maximum request/body size limit on your webhook receiver (reverse proxy, serverless platform, or app server) so it can accept large JSON bodies from post_call_transcription events, and ensure it returns HTTP 200 promptly. Then re‑enable the webhook. (elevenlabs.io)
If large bodies are a constraint:
Use the webhook only as a lightweight trigger and immediately fetch the conversation by ID via GET /v1/convai/conversations/:conversation_id. (elevenlabs.io)
If you enabled audio webhooks, make sure your endpoint can handle chunked transfer; otherwise turn off “Send audio data” to avoid streaming payloads. (elevenlabs.io)
If you need, I can point you to the exact settings pages referenced in the docs or help you design a minimal webhook handler that validates HMAC, returns 200, and offloads retrieval to the Conversations API. (elevenlabs.io)
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