Lỗi error reading skeleton json file for skeletondata asset

After update to 3.8, when I want to create a SkeletonAnimation, it always give me an error at SkeletonJson.c line 939.

This is the line I ended up for (attachmentsMap = Json_getItem(skinMap, "attachments")->child; attachmentsMap; attachmentsMap = attachmentsMap->next) {

And this is how I create my skeleton node. skeletonNode = [SkeletonAnimation skeletonWithFile:skeleton atlasFile:atlas scale:scale];

Anyway, I am using spine version 3.7.94. From what I have discovered, there's a difference about json skeleton from 3.8 and 3.7. In each skin node, there is an attachments. So my question is, how to support skeleton from previous spine version when I need the 3.8 runtime feature like spSkin_addSkin?

Skeleton 'girl' (exported with Spine 3.8.12-beta) may be incompatible with your runtime version: spine-csharp v3.7
UnityEngine.Debug:LogWarningFormat(String, Object[])
Spine.Unity.Editor.AssetUtility:IsSpineData(TextAsset) (at Assets/Spine/Editor/spine-unity/Editor/SpineEditorUtilities.cs:1271)
Spine.Unity.Editor.AssetUtility:ImportSpineContent(String[], Boolean) (at Assets/Spine/Editor/spine-unity/Editor/SpineEditorUtilities.cs:847)
Spine.Unity.Editor.AssetUtility:HandleOnPostprocessAllAssets(String[]) (at Assets/Spine/Editor/spine-unity/Editor/SpineEditorUtilities.cs:673)
Spine.Unity.Editor.SpineEditorUtilities:OnPostprocessAllAssets(String[], String[], String[], String[]) (at Assets/Spine/Editor/spine-unity/Editor/SpineEditorUtilities.cs:218)
UnityEditor.AssetPostprocessingInternal:PostprocessAllAssets(String[], String[], String[], String[], String[])
UnityEditorInternal.InternalEditorUtility:ProjectWindowDrag(HierarchyProperty, Boolean)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)

But I'm sure I've imported the 3.8 package.