ValueError: '' must not contain negative values

This error message is raised when you try to perform an operation that expects a list or array of non-negative values, but the input contains negative values.

For example, if you are trying to take the square root of a list of values using the `math.sqrt()` function, you may get this error if that list contains negative values. The `sqrt()` function can only operate on non-negative values, so it will raise a ValueError if it encounters any negative values.

To fix this error, you need to ensure that your input data contains only non-negative values. You can do this by filtering out any negative values from your input data before performing the operation. Alternatively, you can use a different function or approach that is designed to handle negative values.