If you need to preserve animation, modifiers, or complex scene data, you cannot use free converters. Instead, use a dedicated cloud-based 3ds Max service.
Autodesk does not promote a "downgrader," but if you have a subscription to Autodesk Flex or BIM 360, you can: Convert 3ds Max File To Older Version Online
Cost: Included in higher-tier subscriptions. Not available for free. If you need to preserve animation, modifiers, or
Cause: The .MAX file is corrupted, password-protected, or uses a newer feature not even FBX can interpret.
Fix: Ask the original artist to do a proper "Export to FBX" rather than giving you the native .MAX. Cost: Included in higher-tier subscriptions
Impossible. No online or offline converter can turn a 2025 modifier stack into a 2020 modifier stack if the modifier didn’t exist in 2020. You must install the newer version and collapse modifiers before saving down.