Causes of TLS Handshake Failure
Understanding TLS handshake failures and how to fix them
Table of Contents
Causes of TLS Handshake Failure
TLS handshake failures are caused by: expired certificates (certificates past expiration date), invalid certificate chains (missing intermediate certificates, invalid signatures), certificate validation failures (domain mismatch, untrusted CA), cipher suite mismatches (client and server don't support common cipher suites), protocol version mismatches (TLS version incompatibility), and network issues (timeouts, connection failures).
Common causes include: expired TLS certificates, missing intermediate certificates, invalid certificate signatures, domain name mismatches, and untrusted certificate authorities.
Learn more about TLS handshake, TLS certificates, and certificate chains.
Certificate Issues
Expired Certificates
Expired certificates cause handshake failures - clients reject expired certificates and connections fail. Learn more about certificate expiration.
Domain Mismatch
Certificate domain name mismatch (certificate issued for different domain) causes validation failure and handshake failure.
Untrusted CA
Certificates from untrusted CAs cause handshake failures - clients reject certificates from untrusted certificate authorities.
Revoked Certificates
Revoked certificates cause handshake failures - clients check certificate revocation status and reject revoked certificates.
Invalid Certificates
Invalid certificates (corrupted, malformed) cause handshake failures - clients cannot validate invalid certificates.
Certificate Chain Issues
Missing Intermediate
Missing intermediate certificates cause chain validation to fail - clients cannot verify server certificate without intermediate. Learn more about certificate chains.
Invalid Signatures
Invalid certificate signatures in chain cause validation failure - signatures must be valid for chain to be trusted.
Incomplete Chain
Incomplete certificate chain (missing intermediate or root) causes validation failure and handshake failure.
Untrusted Root
If root CA in chain is not trusted, entire chain is untrusted and validation fails.
Fixing Chain Issues
Fix chain issues by: including all intermediate certificates, verifying certificate signatures, and ensuring root CA is trusted.
Cipher Suite Issues
Cipher Suite Mismatch
If client and server don't support common cipher suites, TLS handshake fails - no encryption method can be agreed upon.
Protocol Version Mismatch
TLS version incompatibility (client supports TLS 1.3, server only supports TLS 1.0) causes handshake failure.
Weak Cipher Suites
Weak cipher suites may be rejected by clients, causing handshake failure if no strong cipher suites are available.
Fixing Cipher Issues
Fix cipher issues by: ensuring client and server support common cipher suites, using modern TLS versions, and avoiding weak cipher suites.
How to Fix Handshake Failures
1. Check Certificate Expiration
Check certificate expiration dates and renew expired certificates before they expire.
2. Fix Certificate Chains
Ensure certificate chains are complete (server → intermediate → root) and all certificates are valid.
3. Verify Certificate Validity
Verify certificates are valid, not expired, match domain names, and are issued by trusted CAs.
4. Check Cipher Suites
Ensure client and server support common cipher suites and use modern TLS versions (TLS 1.2, TLS 1.3).
5. Troubleshoot Network
Troubleshoot network connectivity issues, timeouts, and connection failures that may cause handshake failures.
6. Test TLS Connection
Test TLS connections to verify handshake works correctly after fixes.
