How to fix 'SSLHandshakeException: Received fatal alert: decode_error'?

Question

We have a java application that reads our customers public calendars - for example from google (https://calendar.google.com/calendar/ical/...) or icloud (webcal://p58-caldav.icl

Answer 1

I experienced this same exact issue yesterday with a Java application that tried to connect to https://apple.com:443. I found that a different JDK on a different (Docker) OS fixed the issue. In my specific case, OpenJDK on Alpine didn't work but other Dockerized OpenJDKs (like adoptopenjdk/openjdk11) worked fine.

Answer 2

I faced Received fatal alert: decode_error while connecting with apple cloud urls. I was able to fix it by explicitly setting the protocol as TLS 1.2.

For eg: in kotlin update your spring RestTemplate as below ,

fun restTemplateWithTLS12(): RestTemplate { val requestFactory = HttpComponentsClientHttpRequestFactory() val sslContext = SSLContexts.custom().setProtocol("TLSv1.2").build() val clientBuilder = HttpClients.custom().setSSLSocketFactory(SSLConnectionSocketFactory(sslContext)) requestFactory.httpClient = clientBuilder.build() return RestTemplate(requestFactory) }