Jupyter Notebook 和 Jupyter Lab 运行良好，直到我更新软件包并设置环境。\n此后，JupyterLab 3.0 无法打开。它显示 404 和一条错误消息：
\n[I 18:21:13.532 LabApp] JupyterLab extension loaded from \nC:\\Users\\Alfonso\\AppData\\Roaming\\Python\\Python38\\site-packages\\jupyterlab\n[I 18:21:13.532 LabApp] JupyterLab application directory is C:\\Users\\Alfonso\\AppData\\Roaming\\Python\\share\\jupyter\\lab\n[W 18:21:13.533 LabApp] Error loading server extension jupyterlab\n Traceback (most recent call last):\n File "C:\\ProgramData\\Anaconda3\\lib\\site-packages\\notebook\\notebookapp.py", line 2036, in init_server_extensions\n func(self)\n File "C:\\Users\\Alfonso\\AppData\\Roaming\\Python\\Python38\\site-packages\\jupyterlab\\extension.py", line 226, in load_jupyter_server_extension\n add_handlers(web_app, config)\n File "C:\\ProgramData\\Anaconda3\\lib\\site-packages\\jupyterlab_server\\handlers.py", line 162, in add_handlers\n handlers.append((url_pattern, LabHandler))\n AttributeError: \'NotebookWebApplication\' object has no attribute \'append\'\n[I 18:23:27.282 LabApp] Serving notebooks from local directory: C:\\Users\\Alfonso\n[I 18:23:27.282 LabApp] Jupyter Notebook …