This is a deliberate design choice by Autodesk to encourage upgrades. When a file is saved in a newer version, it may contain scene data, modifiers, or render elements that simply don't exist in the older code base.
For complex scenes with specialized materials, convert or bake materials before conversion to ensure compatibility. Test-export a single mesh first to spot problems early before processing dozens of scenes. Convert 3ds Max File To Older Version Online
When converting, keep an eye out for changes in these specific areas: Status After Down-Conversion What to Expect Clean meshes, polygons, and vertices transfer perfectly. Basic Textures Mostly Safe Standard materials and image maps usually map correctly. Procedural Materials New OSL maps or complex shading networks will break. Animation Rigging This is a deliberate design choice by Autodesk
When web tools or native save-backs fail, exporting your 3D scene to an intermediary format is the most reliable industry workflow. Here are the best formats to use: FBX (Filmbox) Test-export a single mesh first to spot problems
While primarily used to convert .max files to other formats like OBJ or FBX , this can be a vital workaround if you need to open the geometry in an older version of 3ds Max.
how to open 3ds max file latest versions into any older version