"No artists with labels found to put in legend." error when changing the legend size in pyplot

I want to make my legend size bigger in Pyplot. I used this answer to do that. Here is my code.

import matplotlib.pyplot as plt
import seaborn as sns

sns.set_style("whitegrid")
plt.rcParams['figure.figsize'] = [15, 7]

lst = [1,2,3,4,5,6,7,8,9,8,7,6,5,4,3,4,5,6]

plt.plot(lst)
plt.legend(fontsize="x-large") # Here I make it bigger but doesn't work
plt.legend(["This is my legend"])
plt.ylabel('some numbers')
plt.show()

I get this error and I don’t know what is wrong. I don’t understand what "Artist" means here.

No artists with labels found to put in legend. Note that artists whose label start with an underscore are ignored when legend() is called with no argument.

MEDevel.com: Open-source for Healthcare and Education

Collecting and validating open-source software for healthcare, education, enterprise, development, medical imaging, medical records, and digital pathology.

Visit Medevel

>Solution :

"Artist" is a term from matplotlib which Seaborn uses internally:

https://matplotlib.org/stable/tutorials/intermediate/artists.html

Presumably the error message means that there are no items in the legend whose font size can be changed.

Maybe pass the fontsize argument to the same plt.legend call in which you create the legend, or call plt.legend(fontsize=...) after you have created the legend.