Could not find a version that satisfies the requirement Jinja2==2.6 (from versions: ) No matching distribution found for Jinja2==2.6 总是出现类似于这种的报错,是因为网络的问题,要使用国内的镜像源来加速:pip install pymongo -i http://pypi.douban.com/simple/ --trusted-host pypi.douban.com 就可以了,如果还是出错,多试几次,已经解决.