How to fix : SSLCertVerificationError(1, '[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: self-signed certificate in certificate chain)

Python SDK
1

Error

SSLCertVerificationError(1, '[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: self-signed certificate in certificate chain)')

Common Causes

  • Self-signed Certificates: The error explicitly mentions a “self-signed certificate in certificate chain”. This often happens when the server uses a self-signed certificate instead of one issued by a trusted Certificate Authority (CA).

  • Incomplete Certificate Chain: The server might not be sending the complete certificate chain, leading to verification failure.

  • Expired Certificates: If any certificate in the chain is expired, it can cause this error.

  • Outdated CA Certificates: If your local CA certificate store is outdated, it might not recognize valid certificates.

  • Man-in-the-Middle (MITM) Attacks: In rare cases, this could indicate an attempt to intercept your connection.

  • Misconfigured Server: The server might be improperly configured, sending the wrong certificate or an incomplete chain.

  • Corporate Proxies: Some corporate networks use SSL inspection, which can cause this error if not properly configured.

Solutions

1 - Verify the certificate

macOS / Linux

To retrieve SSL/TLS certificates on macOS or Linux, use the following OpenSSL command:
openssl s_client -showcerts -connect api.labelbox.com:443 </dev/null

Windows

(OpenSSL would need to be installed prior)

Use the command:
openssl s_client -showcerts -connect api.labelbox.com:443 < NUL

Those commands will:

  • Connect to api.labelbox.com on port 443.
  • Display all certificates in the certificate chain.
  • Automatically exit after displaying the certificates.

2 - Depending on what the previous command returns you may need to adjust

Most commonly if this issue comes from a python version conflict or a system env dependency you can install pip-system-certs

pip install pip-system-certs