We would need to see the crash log to know if the crash is because the binary file is the wrong version. You need a Skeleton Viewer with the same major and minor version (eg
4.0) as the binary file.
Old atlas files can be read by any version Spine runtime. New atlas files can only be read by version 4.0+. New atlas files can be identified because they don't have indentation.
The first 8 bytes of the binary are a hash, after that is the version as a string stored as a varint then the characters. There is code to read this in the SkeletonBinary class in every runtime.
You can see the version with a hex editor:
You can also likely see the version with a text editor, amongst many unreadable characters.