Troubleshooting Cookie Compatibility Issues Between Brave and Chrome in Modern Web Applications

Developing a seamless user authentication experience across different web browsers can sometimes present unexpected challenges. Recently, I encountered an intriguing issue while working on a full-stack web application deployed with a frontend on Vercel and a backend hosted on Render. Specifically, the authentication cookies I set function correctly in Brave but are blocked in Chrome—despite configuring them with SameSite=None and the Secure attribute, which are critical for cross-site cookies.

The Issue at a Glance

• Brave Browser: Seamless login experience; cookies are properly set and retrieved.
• Chrome Browser: Authentication cookies are being blocked with an error message similar to:
  “Setting this cookie was blocked either due to Chrome flags or browser settings.”

This disparity is particularly perplexing because both browsers support modern cookie attributes, and the same codebase is used across both. The key question is: How can we resolve this inconsistency without resorting to disabling browser flags or security settings?

Understanding the Root Cause

Modern browsers, including Chrome, have tightened restrictions around third-party cookies and cross-site tracking to enhance user privacy. Chrome’s cookie handling policies are influenced by several factors:

• SameSite attribute: Cookies must explicitly declare SameSite=None; Secure to enable cross-site usage.
• Secure attribute: Cookies that are intended for cross-site contexts must be transmitted over HTTPS.
• Browser flags and privacy settings: Users or policies that disable third-party cookies or specific features can interfere.

Despite correct attribute setting, Chrome can still block cookies if certain security policies or flags are enabled, such as:

• Enhanced Cookie Security: Chrome enforces stricter policies that may block cookies even if attributes are set correctly.
• Third-Party Cookie Blocking: Chrome defaults to blocks third-party cookies unless explicitly allowed.
• Browser Flags: Flags like SameSite=None require Secure, and disabling third-party cookies or privacy features might cause blocking.

Strategies for Resolution

1. Verify HTTPS Configuration

Ensure both your frontend (Vercel) and backend (Render) are served over HTTPS. Cookies with Secure attribute are only transmitted over secure connections, so HTTPS is mandatory.

1. Explicitly Set Cookie Attributes

Double-check that your server sets cookies with the following attributes:

“`http