Challenge Not yet complete... here's what's wrong:
We've attempted to insert an opportunity record to test your Verified_Account_for_Closed_Won_Opp validation rule but encountered an unexpected error message. Make sure other validation rules or settings do not block this test.
Not sure what's wrong here, I have tested my validation rule, it's working as expected. So, this is very confusing. I have tried inactivating the other validation rules as well, but the same error pops up.
#Trailhead Challenges
Eric Burté (DEVOTEAM) Forum Ambassador
Hello @Priyodeep Das you should have previous configurations preventing your opportunity from being saved (required field, new validation rule, dependent picklist dependency configuration, failing record triggered flow or before insert/update apex trigger). Remove the extra validation rules, open up all picklist dependencies, and try again. Look for example this thread, or this one to give you ideas.
If you keep on getting the same error, then create a brand new playground (click 3 dot icon next to the Launch button, in the challenge section, and click create playground) and start again the challenge.
Eric