Hi Ali Kholmatov,
Thank you for contacting Syncfusion support.
We were unable to reproduce the issue at our end. However, please ensure the below details in your application,
- In TreeView, the datasource and all other fields should be mapped using fields property.
- Ensure that the id, parentID, hasChildren, and text fields are properly mapped into its respective column names in fields property.
You can refer the below document for more details,
If you are still facing the issue, please let us know in which scenario you are getting this exception? Also, provide us the relevant code snippet or reproducible sample if possible. It would be more helpful to sort out the issue.