the reason why 3dMAX can't save the file and its solution:
cause: the opening format is wrong
solution: open this file with a higher version of max (such as MAX9 and 29), save it as FBX or OBJ format (OBJ is recommended), and then you can open it with MAX8.
In addition, it should be noted that when the 3dmax file cannot be saved due to insufficient hard disk space, or the permission of the default backup file saving path cannot be obtained, a pop-up window "Unable to create backup file" will appear, so be sure to ensure sufficient space when saving.
3DMAX use note
The hard drive where the 3dmax scene model file is located, or the AutoBackup folder itself does not have sufficient read/write permissions, will lead to the failure to save the 3dmax renderings model file.
when the network connection is wrong or you play with the cloud storage drive, the 3dmax model scene file will be in the "cached" state. It can't be saved at this time. Simply put, it was closed before it was cached.
3dmax will also fail to save the model scene file because of an error. It is planned that when saving the 3dmax model file in the cloud storage drive, the cloud storage drive will synchronize the automatic backup file of the rendering scene before saving.