This stack is for interpreting Rails error pages. We learn from our mistakes. This will likely not be the last time you see this particular flavor of error. When you get an error page, and something clicks in your mind, capture it. Translate what the error is really telling you. When looking at a Rails error with a mentor or senior developer, ask them to explain what they see in the error. What are the cues, the key terms and phrases, and how do they leverage this information to resolve the issue.