The truth value of a DataFrame is ambiguous.

This error message usually occurs when you are trying to perform a boolean operation on a Pandas DataFrame and the result cannot be unambiguously determined.

It can happen if you are trying to check if a DataFrame is empty or if a condition is true for the entire DataFrame. In these cases, the DataFrame might contain both True and False values, but the overall truth value cannot be determined without additional information.

To resolve this issue, you can try to specify the axis along which the operation should be performed or use a more specific operation that returns a single boolean value. For example, you can use the `.all()` method to check if all values in the DataFrame are True or the `.any()` method to check if any value is True.