We have seen this error before with spatial index corruption.
Try following workflow:
1. In SQL Server Management Studio, run the below query as "dbo" or "sa" user to find the Object_id of the problematic feature class.
select * from sys.indexes where name = ‘S4717_idx’;
2. Then use object_id to identify the feature class:
select * from sys.objects where OBJECT_ID= 'xxxxx';
3. Rebuild the spatial index for that feature class.