Ensure the installation isn't being blocked by checking the Image File Execution Options in your Windows Registry as suggested by Autodesk technical support .
To summarize:
Opening a scene referencing another file results in "Error: Node type 'unknown' not recognized." The Solution: This is usually due to mismatched plugin versions. Go to Windows > Settings/Preferences > Plug-in Manager . Ensure fbxmaya.mll and objExport.mll are checked "Loaded" and "Auto-load." Then, delete the referencenodes history before saving. autodesk maya 20185 fixed