[Bug]: Incompatible with urllib3 2.x - AttributeError: 'HTTPResponse' object has no attribute 'getheader'

[daskycodes]

What happened?

The latest version of the API library (2.2.1) throws an exception when creating a notification with urllib3 2.x installed.

Error:
AttributeError: 'HTTPResponse' object has no attribute 'getheader'

The issue is in onesignal/rest.py line 43, where RESTResponse.getheader() calls self.urllib3_response.getheader(). This method was removed in urllib3 2.0 (April 2023).

The package declares urllib3>=1.25.3 with no upper bound, but the code is not compatible with urllib3 2.x.

Steps to reproduce?

1. Install onesignal-python-api==2.2.1 with urllib3>=2.0 (e.g., urllib3==2.5.0)
2. Create and send a notification using the API
3. Observe AttributeError: 'HTTPResponse' object has no attribute 'getheader'

What did you expect to happen?

The notification should be sent successfully. Either:

1. The SDK should be updated to use the urllib3 2.x API (.headers.get() instead of .getheader())
2. Or the package should pin urllib3>=1.25.3,<2 until fixed

Code of Conduct

• I agree to follow this project's Code of Conduct

[plisker]

+1 to this issue. Caused an unexpected outage recently in a project I'm working on.

Also, want to express a strong preference between the two remediation options that the SDK is updated to use urllib3 2.6.0 or higher given recent CVEs CVE-2025-66471 and CVE-2025-66418.