"tlsv1 alert unknown ca" in node.js - node.js

Question

For the last 5 days I've got a lot of weird errors in my app's logs. Here is the stack trace:
Error: 140428615087936:error:14094418:SSL routines:SSL3_READ_BYTES:tlsv1 alert unknown ca:../deps/openssl/openssl/ssl/s3_pkt.c:1234:SSL alert number 48
at CleartextStream._pusher (tls.js:674:24)
at SlabBuffer.use (tls.js:217:18)
at CleartextStream.CryptoStream._push (tls.js:501:33)
at SecurePair.cycle (tls.js:898:20)
at EncryptedStream.CryptoStream.write (tls.js:285:13)
at Socket.ondata (stream.js:38:26)
at Socket.EventEmitter.emit (events.js:96:17)
at TCP.onread (net.js:397:14)
It is the same for all these errors. Node.js version is 0.8.24.
Does anybody know why it could happen?

Answer 1

We've solved that problem. It happened because of minor misconfiguration in SSL certificates on our other API server (which node.js talked to).
To check your SSL configuration you can use one service by SSL Labs. In our case there was this warning (incomplete chain issues):
To fix it you should do the following (excerpt from nginx docs):
Some browsers may complain about a certificate signed by a well-known
certificate authority, while other browsers may accept the certificate
without issues. This occurs because the issuing authority has signed
the server certificate using an intermediate certificate that is not
present in the certificate base of well-known trusted certificate
authorities which is distributed with a particular browser. In this
case the authority provides a bundle of chained certificates which
should be concatenated to the signed server certificate. The server
certificate must appear before the chained certificates in the
combined file:
$ cat www.example.com.crt bundle.crt > www.example.com.chained.crt
The resulting file should be used in the ssl_certificate directive:
server {
listen 443 ssl;
server_name www.example.com;
ssl_certificate www.example.com.chained.crt;
ssl_certificate_key www.example.com.key;
...
}
The key part is concatenation of certificate files. Errors in node.js app disappeared just after we've made that changes.