github添加公钥后报错：sign_and_send_pubkey: signing failed: agent refused operation

问题描述：在github已有的一个私有仓库中添加了公钥，但是报错“sign_and_send_pubkey: signing failed: agent refused operation”，并且提示“Please make sure you have the correct access rights and the repository exists.”，如下图：

解决办法：

eval "$(ssh-agent -s)"
ssh-add