Module- Customize a Salesforce Object Unit- Create validation rule でのエラー

6月に入って目立つエラーです。解決策はよく分からない

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.

• 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.