Could not find a version that satisfies the requirement pyqt5 (from labelimg) (from versions: none)

这个错误提示表明在安装labelimg时，需要安装pyqt5这个包，但是当前环境中没有找到对应的版本。解决这个问题的方法是更换pip源并指定python解释器，具体步骤如下：
1. 打开命令行工具，输入以下命令更换pip源：

pip config set global.index-url https://pypi.douban.com/simple/

2. 然后再输入以下命令安装pyqt5：

C:\Users\13286\AppData\Local\Programs\Python\Python36\python.exe -m pip install PyQt5 -i http://pypi.douban.com/simple/ --trusted-host pypi.douban.com

3. 如果安装成功，会显示类似于“Successfully installed PyQt5-Qt5-5.15.2 PyQt5-sip-12.11.0 pyqt5-5.15.7”的信息。

相关问题

Could not find a version that satisfies the requirement PyQt5.QtWebEngineWidgets (from versions: none)

这个错误提示是因为在安装 PyQt5 时没有安装 QtWebEngine 模块。可以通过以下命令安装：

pip install PyQtWebEngine

如果还是出现类似的错误提示，可以尝试更新 pip 和 PyQt5：

pip install --upgrade pip
pip install --upgrade PyQt5

Could not find a version that satisfies the requirement PyQt5==5.11.3 (from versions: none)

The issue you are experiencing is likely due to PyQt5 version 5.11.3 no longer being available or compatible with your system. You may need to either upgrade to a newer version of PyQt5, or use a different version that is compatible with your system. It's also possible that there may be other dependencies or requirements that need to be fulfilled in order to install PyQt5. If you continue to experience issues, I recommend seeking further guidance from a technical support forum or community.