Auto Base Upgrade: Broken after May update

The plugin of Auto Base Upgrade is broken after May update.

05/04 20:24:19 | There was an issue connecting to ""! Some address placeholders may not be available. Code: 0
05/04 20:24:20 | Error while compiling: AutoBaseUpgrade.cs(392,34): error CS1061: Type `BuildingBlock' does not contain a definition for `GetGrade' and no extension method `GetGrade' of type `BuildingBlock' could be found. Are you missing an assembly reference?