Help with exercise MULTIPLE LINEAR REGRESSION Introduction to Multiple Linear Regression

Hello everyone,
i’m currently doing the machine learning exercise:
Introduction to Multiple Linear Regression

with the following code:

import codecademylib3_seaborn

import matplotlib.pyplot as plt
import numpy as np
import pandas as pd

from mpl_toolkits.mplot3d import Axes3D

from sklearn.linear_model import LinearRegression
from sklearn.model_selection import train_test_split

streeteasy = pd.read_csv("")

df = pd.DataFrame(streeteasy)

x = df[['size_sqft','building_age_yrs']]
y = df[['rent']]

x_train, x_test, y_train, y_test = train_test_split(x, y, train_size = 0.8, test_size = 0.2, random_state=6)

ols = LinearRegression(), y_train)

# Plot the figure

fig = plt.figure(1, figsize=(6, 4))

elev = 43.5
azim = -110

ax = Axes3D(fig, elev=elev, azim=azim)

ax.scatter(x_train[['size_sqft']], x_train[['building_age_yrs']], y_train, c='k', marker='+')

ax.plot_surface(np.array([[0, 0], [4500, 4500]]), np.array([[0, 140], [0, 140]]), ols.predict(np.array([[0, 0, 4500, 4500], [0, 140, 0, 140]]).T).reshape((2, 2)), alpha=.7)

ax.set_xlabel('Size (ft$^2$)')
ax.set_ylabel('Building Age (Years)')
ax.set_zlabel('Rent ($)')


# Add the code below:

I redue all the code in VS code, with that it works for me better to connect the content and play around a bit.
Unfortunately in VS code i receive the following message:

UserWarning: X does not have valid feature names, but LinearRegression was fitted with feature names

does someone has an idea how to solve that?