I am facing Org error in completing the challenge of the last step "Use External Services in a Flow" for the Module " External services" . My flow is working fine . Only when I try to verify , trailhead gives below error . 

Challenge not yet complete in CRM ADMIN VF

There was an unexpected error while verifying this challenge. Usually this is due to some pre-existing configuration or code in the challenge Org. We recommend using a new Developer Edition (DE) to check this challenge. If you're using a new DE and seeing this error, please post to the developer forums and reference error id: ADOGHNYK

I am using an existing playground . I really do not want to to start from the scratchand wanted to understand if there is any way to get rid of this ? If nothing helps , I will go ahead and create a new Org :( .  With this Challenge , i will complete the Admin intermediate Trail , and so really want a quick solution . Thank you in advance .