An unexpected error occurred while inserting Opportunity records and we couldn't check your work. Make sure Opportunity records can be inserted in this org, and click "Check Challenge" again. If this continues, contact the Trailhead Help team.

Hi Nabendra,

Try unchecking the checkbox "deselect the checkbox Restrict picklist to the values ​​defined in the value set" in Picklist (Multi-Select) Options in the settings for "Close Reason".

Thanks