Me too, sometimes it works but i do nothing and then again I have this error. I think it's an Opera Gx problem and they have to fix it.

With other browsers it works fine.

My Opera Gx just update to version 73.0.3856.434 and for now Gmail is working fine without the workaround. Someone else?

Edit:

LVL 2 (core: 73.0.3856.434) – 2021-04-15

[FIX] Google Mail certificate issue hot-fix(please update to this version via opera://about in GX browser or get it from opera.com/gx)

My Opera Gx just update to version 73.0.3856.434 and for now Gmail is working fine without the workaround. Someone else?

Edit:

LVL 2 (core: 73.0.3856.434) – 2021-04-15

[FIX] Google Mail certificate issue hot-fix(please update to this version via opera://about in GX browser or get it from opera.com/gx)

@burnout426 It works dije. Thanks!

I've opened a bug report issue to Opera Gx today but they don't give me a reply. I'm still waiting

I report the issue to Opera (DNAWIZ-129020) Gmail Issue - NET::ERR_SSL_PINNED_KEY_NOT_IN_CERT_CHAIN

We'll see if they say something. Because it's just in Opera.

Buenas! Si, me pasa lo mismo desde ayer. Por momentos funciona devuelta de la nada y por momentos me vuelve a tira el mismo error.

En otros navegadores funciona sin problemas.

La falla me pasa en varias PC's así que parece ser un tema de Opera, deberían arreglarlo.

Me too, sometimes it works but i do nothing and then again I have this error. I think it's an Opera Gx problem and they have to fix it.

With other browsers it works fine.