ValueError: continuous is not supported

I am working on a regression problem and building a model using Random Forest Regressor but while trying to get the accuracy I am getting ValueError: continuous is not supported.

train=pd.read_csv(rC:\Users\DELL\OneDrive\Documents\BigMart data\Train.csv)
test=pd.read_csv(rC:\Users\DELL\OneDrive\Documents\BigMart data\Test.csv)
df=pd.concat([train,test])
df.head()

After Data Preprocessing and Visualization, I have tried to build the model :

Please help with the error