can you tell me why the geometry is invalid?
He did not encounter any errors in the construction phase.
It happens often with Dendro outputs. Since Rhino V6, Rhino is more stringent with mesh validity.
You can play with the I Isovalue settings of Dendro and also the adpativity (set to 0). And also the steps.
You could also try to smooth the mesh using Dendro Smooth.
Or repair mesh inside Rhino.
This is the fourth thread from you on this subject!