First [reported by Schniki12](https://forum.sailfishos.org/t/whisperfish-the-unofficial-sailfishos-signal-client/3337/573?u=rubdos) on the forum. ``` [2022-05-27T11:57:17Z DEBUG libsignal_service_actix::push_service] HTTP request PUT https://chat.signal.org/v1/messages/da3c83ad-8c45-4d14-87d5-xxxxxxxxxxxx [2022-05-27T11:57:18Z DEBUG libsignal_service_actix::push_service] AwcPushService::put response: ClientResponse HTTP/1.1 428 Precondition Required headers: "connection": "keep-alive" "date": "Fri, 27 May 2022 11:57:18 GMT" "content-type": "application/json" "content-length": "88" "retry-after": "86400" "x-signal-timestamp": "1653652638324" [2022-05-27T11:57:18Z TRACE libsignal_service_actix::push_service] Unhandled response with body: Ok(b"{\"token\":\"6090bb08-659a-47ea-824e-xxxxxxxxxxxx\",\"options\":[\"recaptcha\",\"pushChallenge\"]}") [2022-05-27T11:57:18Z ERROR harbour_whisperfish::worker::client] Sending message: Error sending message: Unexpected response: HTTP 428 ``` Suggested workaround, because captchas (#118, #378) still crash the webrender, is to (re)use the `MessagePipe` that is already used for receiving messages for also sending messages. I feel like the PUT endpoint is rate limited only on new connections, and that Signal prefers the pipe at this point. This can first be checked in the Signal-Android sources.