I was working on something today and there was a problem with Error loading package list: Request failed with status code 403.
Solution:
1. Click settings, and then click Project Interpreter in the figure below
2. Click the plus sign on the right, click Manage Repositories, and change the source to Tsinghua source. Delete the original source. Do not use Tsinghua source and the original source together. Delete one of the two.
Tsinghua source website https://pypi.tuna.tsinghua.edu.cn/simple/
Ali source https://mirrors.aliyun.com/pypi/simple/
This is my solution to the pro test and effective!