ValueError: Expected 1D or 2D array, got 3D array instead

This error message is raised when a function or method expects a 1D or 2D array as input, but instead receives a 3D array.

A 1D array is a linear array with a single row or column, while a 2D array is a matrix with multiple rows and columns. A 3D array, on the other hand, has multiple layers or "slices" of 2D arrays.

The most common cause of this error is passing a 3D array to a function that expects a 2D array. To fix this error, you may need to reshape or flatten the input array to convert it to a 2D or 1D array, depending on the requirements of the function. Alternatively, you may need to modify the function to handle 3D arrays.