Import error in Spine Editor 3.5.51 despite JSON working in Viewer

m5n1kgw

Hello,

I’m currently working on reconstructing Spine project data using only old JSON export files that were originally generated for Spine Editor 3.5.51, as no other formats (such as .spine) are available.

During this process, I encountered an issue where certain JSON files open and play correctly in Skeleton Viewer (v3.5.51), but result in an import error when opened in the Spine Editor.

The error message shown in the Editor is:

“An error occurred while importing the skeleton. Please be sure to choose a valid skeleton JSON or binary file.”

Here is what I’ve confirmed so far:

The "spine" version inside the JSON is correctly set to "3.5.51"

Required sections like "skeleton", "bones", "slots", "skins", and "animations" are all present

Encoding is UTF-8 (without BOM), and there are no syntax errors

Both PrettyPrint and Minified versions of the JSON fail to import

The file size is around 500KB, while other working files are approximately 200KB

Attempting to open the file in Spine Editor version 3.6.x also fails

Even when trimming the file down to just "skeleton", "bones", and "slots" with placeholder attachments, the import fails

Due to client confidentiality, I’m unable to provide the actual file, but I would appreciate any insight into possible causes or known limitations in Spine 3.5.51 that might result in this issue.

This message was translated using ChatGPT, so if anything is unclear or confusing, I’d greatly appreciate your feedback.

Thank you very much for your support.

Misaki

m5n1kgw Unfortunately, as Spinebot mentioned, we are unable to investigate the issue without receiving the actual file.
However, even if we were to investigate on our end, the only thing we could try is to see if we can import the JSON file with the contents minimized as much as possible. If that still doesn't work, this issue may be difficult to resolve.

If you haven't tried it yet, you could try deleting all the animation-related sections described in the JSON file and importing only the skeleton, or try importing the skeleton with some elements removed to see if that works. Even if the versions match and you encounter this import error, it is possible that some elements contain invalid information. If you can identify what that is, you may be able to import the JSON file.

Spinebot

It seems you are experiencing an issue where JSON files that work in the Skeleton Viewer do not import correctly into the Spine Editor. This could be due to several factors, such as specific data within the JSON that the Editor cannot process, even though the Viewer can. One potential cause could be discrepancies in how the Viewer and Editor handle certain data structures or attributes. Since you have confirmed that the JSON version and structure are correct, and the issue persists even with minimal data, it might be related to specific data content or size limitations. Unfortunately, without the ability to examine the file directly, it is challenging to pinpoint the exact cause. You might consider checking for any unusual data patterns or attributes that could be causing the import to fail.

m5n1kgw

Thank you very much for your response and helpful suggestions, especially despite the limitation of not being able to share the file.

Following your advice, I tried reducing the JSON to its minimal structure (keeping only skeleton, bones, slots, and default skin).
With that version, I was able to import it successfully in Spine Editor 4.2 — the basic bone structure displayed correctly.

However, the same file still failed to import in Spine Editor 3.5.51.

I’ll keep investigating on my end a bit more based on this result.
Thanks again!