urllib3 2.6.x incompatibility: AttributeError: 'HTTPResponse' object has no attribute 'getheaders' (SDK calls removed API)

[eseifert]

Summary

With urllib3>=2.6.0, the Brevo/SendinBlue Python client fails at runtime with:

AttributeError: 'HTTPResponse' object has no attribute 'getheaders'

This happens when ApiException is raised and the SDK calls http_resp.getheaders().

Evidence / references

• urllib3 2.6.0 removed HTTPResponse.getheaders() / getheader() in favor of HTTPResponse.headers / HTTPResponse.headers.get(...) (see release notes, removal #3622):
  https://github.com/urllib3/urllib3/releases/tag/2.6.0
• urllib3 v2 migration guide also notes the deprecation & planned removal:
  https://urllib3.readthedocs.io/en/2.5.0/v2-migration-guide.html
• SDK currently calls http_resp.getheaders() in sib_api_v3_sdk/rest.py (and wraps urllib3 responses):
  https://github.com/sendinblue/APIv3-python-library/blob/master/sib_api_v3_sdk/rest.py

Reproduction

pip install "sib-api-v3-sdk==7.6.0" "urllib3>=2.6.0"

Trigger any API error (401/403/etc.) so the SDK raises ApiException, e.g. invalid API key:

import sib_api_v3_sdk
from sib_api_v3_sdk.rest import ApiException

cfg = sib_api_v3_sdk.Configuration()
cfg.api_key["api-key"] = "invalid"

api = sib_api_v3_sdk.TransactionalEmailsApi(sib_api_v3_sdk.ApiClient(cfg))

try:
    api.get_smtp_templates()
except ApiException as e:
    print("caught:", e)

Proposed fix (backwards compatible)

Update the SDK response wrapper to use .headers when getheaders() / getheader() are not available:

# sib_api_v3_sdk/rest.py

def getheaders(self):
    if hasattr(self.urllib3_response, "getheaders"):
        return self.urllib3_response.getheaders()
    return self.urllib3_response.headers

def getheader(self, name, default=None):
    if hasattr(self.urllib3_response, "getheader"):
        return self.urllib3_response.getheader(name, default)
    return self.urllib3_response.headers.get(name, default)

Workaround

Pin urllib3 until the SDK is regenerated/fixed:

urllib3<2.6