Git: Agent admitted failure to sign using the key. Permission denied (publickey).

After configuring SSH keys have been reported following error will execute git clone:

Agent admitted failure to sign using the key. 
Permission denied (publickey).

Execution ssh -T git@domainwill report this error, the workaround:
Use ssh-addthe command to add a key to ssh-agent's cache:

 ssh-add   ~/.ssh/id_rsa 

Note: Change the name id_rsa different according to the individual keys

参考：
Git: Agent admitted failure to sign using the key. Permission denied (publickey). fatal: Could …