While typing up my answer for Where are Vicious Weapons detailed? I noticed there's an inconsistency with the description for Vicious Weapon between what's written in the DMG and the SRD.
The DMG states:
When you roll a 20 on your attack roll with this magic weapon, the target takes an extra 7 damage of the weapon's type.
Whereas the SRD says:
When you roll a 20 on your attack roll with this magic weapon, the target takes an extra 2d6 damage of the weapon's type.
I checked the DMG errata and there hasn't been a correction added there.
Has this been updated elsewhere and which text is meant to be the correct damage for Viscious Weapon: 7 or 2d6?
P.S I know the average roll of 2d6 is going to be about 7 anyway but that's not the point.
Best Answer
There has not been any word of god statement on the matter...
...and the v1.1 DMG Errata (May 2016) doesn't cover it.
However, on Jun 7 '17 the Vicious Weapon entry on D&D Beyond said "2d6". As of June 7 2018 (possibly earlier), D&D Beyond was changed to match the printed DMG, "7".
...but it is now clear the SRD is in err.