I’m using Firefox on a work Macbook. Occasionally, I encounter sites that won’t load properly on Firefox, but everything works OK on Chrome. The latest example is https://miro.com
The system is configured to push all network traffic through a corporate VPN (ZScaler), and I can’t turn it off.
There’s one important setting that is changed in about:config
- security.enterprise_roots.auto-enabled= true <- that’s needed to trust corporate certificate roots. VPN is basically performing MITM attack on the whole network traffic.
The situation is:
- Chrome on VPN – site loads fine.
- Firefox on a personal computer – works fine.
- Firefox on VPN – site doesn’t load properly.
I have noticed 2 symptoms in the network tab:
- Some requests (e.g. for fonts) are failing due to CORS.
- Some requests load for several seconds and then return empty responses – “0B” in the “Transferred” and “Size” columns,
I’ve already tried the usual things:
- clear cache
- turn off all the extension
- run in incognito mode.
My questions:
- What are the differences between Firefox and Chrome in CORS handling (or other Network-related stuff) that could explain such behaviour?
- What other steps could I take to diagnose this issue?