ArgumentException: JSON parse error: Invalid value how to solve?

Question

Unity

I write all the texts for my game to a JSON file, after I rewrote it, I started getting this error
ArgumentException: JSON parse error: Invalid value.
UnityEngine.JsonUtility.FromJson (System.String json, System.Type type) (at <1386288601af43018501cce2912f52f4>: 0
)
) (at Assets/Script/Lang Script/LangSystem.cs:41)
LangSystem.Awake () (at Assets/Script/Lang Script/LangSystem.cs:27)

But as soon as I remove a certain fragment from it, it starts working. Please tell me what could be wrong and how to fix it?