Block a contact
POST/api/sessions/:sessionId/contacts/:contactId/block
Block a contact
Request
Responses
- 200
- 409
- 503
Contact blocked
The session is not connected — an engine exists for it but is not ready: disconnected, reconnecting, or still initializing, so the request never reached WhatsApp. Wait for ready and retry. A session that was never started answers 400 instead, and the session lifecycle routes answer 409 for a conflicting state rather than this. One window answers this while the session still reads ready: WhatsApp Web periodically reloads its own page and the engine re-injects into it — for those few seconds the answer is a 409 naming the reload; retry shortly.
WhatsApp did not answer within the request budget. The change may or may not have been applied — the gateway stopped waiting for a confirmation that never came.