Sharing my solution of DENDRO plugin throwing you « Unable to load DLL ‘DendroAPI.dll’ » error.
It can be solved by turing COFF off. Thing you can do in rhino by typing the command : DrasshopperDevelperSettings and then unchek Mermory Load option.
Now, I don’t recommande using this method as other Grasshopper plugin will require COFF on (like elefront, pufferfish, etc).
Instead, open grasshopper, go to file > solver > seek for DENDROGH and change the Load Mechanism to the orange disc.
Don’t forget to restart Rhino.