The following reasons can cause JSON validation to fail.
Error causes that may be difficult to pinpoint:
1. Non-numeric key-value pairs in the JSON string are not enclosed in double quotes.
2. The presence of tab characters like \t in the JSON, which look like spaces but can cause validation to fail; removing them can resolve the issue.
3. The presence of a BOM (Byte Order Mark) in the editor can also cause JSON validation to fail.