502 api network_error ai_generated true

502 Bad Gateway: SSL handshake failed between ALB and target

ID: api/http-502-bad-gateway-aws-alb-ssl-handshake

Also available as: JSON · Markdown · 中文
82%Fix Rate
87%Confidence
1Evidence
2023-11-20First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
AWS ALB 2023+ active — — —
NGINX 1.24+ active — — —
Tomcat 10.x active — — —
Java 17+ active — — —
Go 1.21+ active — — —

Root Cause

AWS Application Load Balancer (ALB) could not establish an SSL/TLS connection with the target because the target's certificate is self-signed, expired, or the cipher suite is incompatible.

generic

中文

AWS 应用负载均衡器 (ALB) 无法与目标建立 SSL/TLS 连接，因为目标证书是自签名的、已过期或密码套件不兼容。

Official Documentation

https://docs.aws.amazon.com/elasticloadbalancing/latest/application/load-balancer-troubleshooting.html#ssl-handshake-failed

Workarounds

  1. 90% success Install a trusted certificate on the target (e.g., from Let's Encrypt). For testing, use a self-signed certificate but upload it to ACM and attach to the ALB target group as a custom trust store. Example using OpenSSL to generate a self-signed cert for ACM: openssl req -new -newkey rsa:2048 -days 365 -nodes -x509 -keyout server.key -out server.crt Then import server.crt into ACM and configure the target group to trust it. 
    Install a trusted certificate on the target (e.g., from Let's Encrypt). For testing, use a self-signed certificate but upload it to ACM and attach to the ALB target group as a custom trust store. Example using OpenSSL to generate a self-signed cert for ACM:
openssl req -new -newkey rsa:2048 -days 365 -nodes -x509 -keyout server.key -out server.crt
Then import server.crt into ACM and configure the target group to trust it.
  2. 80% success Update the target's cipher suite to match ALB's supported list. ALB supports TLS 1.2+ with ciphers like ECDHE-RSA-AES128-GCM-SHA256. On NGINX, add: ssl_ciphers 'ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256'; 
    Update the target's cipher suite to match ALB's supported list. ALB supports TLS 1.2+ with ciphers like ECDHE-RSA-AES128-GCM-SHA256. On NGINX, add: ssl_ciphers 'ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256';

中文步骤

  1. Install a trusted certificate on the target (e.g., from Let's Encrypt). For testing, use a self-signed certificate but upload it to ACM and attach to the ALB target group as a custom trust store. Example using OpenSSL to generate a self-signed cert for ACM:
openssl req -new -newkey rsa:2048 -days 365 -nodes -x509 -keyout server.key -out server.crt
Then import server.crt into ACM and configure the target group to trust it.
  2. Update the target's cipher suite to match ALB's supported list. ALB supports TLS 1.2+ with ciphers like ECDHE-RSA-AES128-GCM-SHA256. On NGINX, add: ssl_ciphers 'ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256';

Dead Ends

Common approaches that don't work:

  1. 90% fail

    The error is due to misconfiguration, not transient state.

  2. 70% fail

    AWS does not allow insecure connections from ALB to targets.