I recently upgraded my Mac from macOS Sequoia to Ventura because of the “Apple System Data” storage issue. After a fresh install, I couldn’t log in to ChatGPT—getting a persistent Error 400 Route. I tried different browsers and troubleshooting, but nothing worked.

After some research, I realized that ChatGPT may no longer support older OS versions, similar to how older iPhones with outdated iOS face restrictions. When I installed the latest macOS Tahoe, I was finally able to log in to my ChatGPT Premium account.

While I understand the need for compatibility and security, it’s frustrating that users are forced to upgrade their systems—even ones that were previously working fine—just to access services they already pay for.