I was doing some reorganizing and broke a chest behind my Nether Portal block and the portal disappeared. The information I had was that portal blocks are unbreakable, I did not even hit it and it is gone.

Very Strange.

~CyberDrifter

Did you break blocks next to it? That breaks them if you did

I did in fact break a chest next to it. I was however told a couple months ago by a Mod online that you can't break a portal block once it has been placed. I guess that was bad info.

It's bad info. If you place a block on top of the portal block it will also break.

It's kind of like a door. If you break the bottom block of a door, the door breaks. Wherever you place the portal, any adjacent block will break. It's always been this way, to the extent of my knowledge. Happens to me a lot in single player (I have to always reignite the portal there when I try to renovate the portal room).

Portal blocks are destroyed when a block next to one is placed or broken.