[▲ Vercel Community](/) · [Categories](/categories) · [Latest](/latest) · [Top](/top) · [Live](/live) [Help](/c/help/9) # Vercel site net::ERR_CERT_AUTHORITY_INVALID error on corporate networks 1 view · 0 likes · 2 posts Luke Hinds (@lukehinds) · 2026-04-08 Hello, Our Vercel site is producing `net::ERR_CERT_AUTHORITY_INVALID` for some users, who appear to have something like Corporate Defender (Fortinet). I checked against [https://www.ipqualityscore.com](https://www.ipqualityscore.com) and it states: - **Fraud Score:** 100 - **Connection:** VPN The domain is `https://nono.sh` **Error:** > **net::ERR_CERT_AUTHORITY_INVALID**  system (@system) · 2026-04-08 The domain troubleshooting guide can help with most custom domain configuration issues. You might be able to use that guide to solve it before a human is available to help you. Then you can come back here and share the answer for [bonus points](https://community.vercel.com/t/introducing-the-vercel-leaderboard/1358). https://vercel.com/docs/projects/domains/troubleshooting You can also use [v0](https://v0.dev/) to narrow down the possibilities.