Why is my custom metric or attribute returning an error when I add it to a query?

Question

I made a custom metric or attribute, and got the green check mark in the formula editor. However, when I try to use my new metric or attribute in a query, I get the following error:

The set of calculations [0] isn’t valid. Adjust the calculation and try again. (Error code: c2b7007d)

Answer

The error checker in the formula editor only checks the syntax of the formula. This means there's another error in the formula. Typically this means that the formula is referencing a field that doesn't exist. If you see this error, you should edit your formula and double-check that all attributes and metrics referenced in the formula are spelled correctly. Also, you should note that fields in the query editor are case-sensitive, so you should also make sure that all your attributes and metrics are using the correct case.