I remember someone having a probelm with black specular reflections, I’m having the same problem here, and I think that someone discovered how to solve it, some ideas please?
Basically the problem is that when the light is too bright (like the sun) the reflection is black, so it gives a black specular.
Cheers!
Yes, I found it just before I saw your answer. 
Cheers!
And there is a link to this thread in that article:
https://forum.corona-renderer.com/index.php/topic,6883
There are some workaround suggested there.
Yes, I configured the glass as thin glass, and that solved everything This should be fixed ASAP I think, because it renders imposible to use proper glass in a room 
Cheers.
Agreed, this needs fixing ASAP!
You don’t need to use thin glass. You can use rayswitch material. In this message there is an example how to do it (.max file):
IMHO this should be even higher priority than material glossy darkening on edges.
Having to use trick for regular refractive glass on architectural elements is quite debilitating given this is like the absolute basic of architectural scene.
Neither thin nor rayswitch provide correct result visually, outside of being quite pain in ass to do (as specially rayswitch).
I created a thread about it with similar comment long time ago and there was virtually no response.
Neither thin nor rayswitch provide correct result visually, outside of being quite pain in ass to do (as specially rayswitch).
Sure, that’s why I only recommend this as a temporary workaround.
Well, I’ve done my fair share of complaining about it, nothing we can do until the next core build (at least according to Ondra).
As Juraj mentioned here and I did in the main thread - this is important. In scenes where you have some sort of a frosted window (bathrooms), skylight (lobbies, etc) or a roof or whatever you’re basically f**ked because there is no way to achieve correct speculars, even with certain fudges. You either give up the lighting or the glass.
This is a scene breaker as far as I’m concerned.
I am just musing, not necessary correcting you or anything :- )
Regarding response. I am honestly surprised. Any architecture with glass walls which is pretty common nowadays should make it very obvious, but maybe people don’t notice what is wrong ?
Sometime the error is fairly subtle, and unless you make correcture (thin glass or rayswitch), most might not notice it.
The curious thing is that the project I’m rendering now uses a scene renderd in the past with some alpha (A7 or some dayli build near A7) and there was no problem in the past, because the scene rendered fine, and now when I’m reusing the scene and upgrading it, without changing a thing in the glass material I have this problem.
Cheers.