reference error id: LJOFHGKY

I was trying to solve a challenge from the topic Customize Compact Layouts and then i faced this problem. It has been a month or two i am learning salesforce so not able to find where exactly problem lies. Please help me out

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: LJOFHGKY