curl / Mailing Lists / curl-users / Single Mail
Buy commercial curl support from WolfSSL. We help you work out your issues, debug your libcurl applications, use the API, port to new platforms, add new features and more. With a team lead by the curl founder himself.

SSL_ERROR_SYSCALL in connection to

From: Paulo Roberto Tomasi via curl-users <>
Date: Wed, 13 Nov 2019 20:23:09 -0300


I would like help to solve an error related to cURL x Telegram:

# cURL version:
root_at_zabbix-server:/# curl -V
*curl 7.67.0* (x86_64-pc-linux-gnu) libcurl/7.67.0 OpenSSL/1.0.2g
Release-Date: 2019-11-06
Protocols: dict file ftp ftps gopher http https imap imaps pop3 pop3s rtsp
smb smbs smtp smtps telnet tftp
Features: AsynchDNS HTTPS-proxy IPv6 Largefile libz NTLM NTLM_WB SSL
TLS-SRP UnixSockets

# Linux version:
root_at_zabbix-server:/# lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: *Ubuntu 16.04.6 LTS*
Release: 16.04
Codename: xenial


When I try curl -v -I

root@zabbix-server:/# curl -v -I
* Trying
* Trying 2001:67c:4e8:f004::9:443...
* Immediate connect fail for 2001:67c:4e8:f004::9: Cannot assign requested
* Connected to ( port 443 (#0)
* ALPN, offering http/1.1
* Cipher selection:
* successfully set certificate verify locations:
* CAfile: /etc/ssl/certs/ca-certificates.crt
  CApath: none
* TLSv1.2 (OUT), TLS header, Certificate Status (22):
* TLSv1.2 (OUT), TLS handshake, Client hello (1):
* OpenSSL SSL_connect: SSL_ERROR_SYSCALL in connection to
* Closing connection 0
curl: (35) OpenSSL SSL_connect: SSL_ERROR_SYSCALL in connection to


cURL gives me *SSL_ERROR_SYSCALL* error.

If I test curl -v -I, everything seems ok.

Could you help me solve this? Thanks

Received on 2019-11-14