I am new to ubuntu and I just installed it. when I tried to install git using "apt-get install git" I received error with "unable to connect". Then I found this question and did as what the question said. I installed git without any problem(I also installed vim and postgresql, no problem). But I received the following the error when I do "apt-get update".

W: GPG error: http://extras.ubuntu.com precise Release: The following signatures were invalid: BADSIG 16126D3A3E5C1192 Ubuntu Extras Archive Automatic Signing Key <ftpmaster@ubuntu.com>

Then I replaced the sources.list with the original one--the previous one when I had problem using apt-get install. and the strange thing is that I can use apt-get install(all i did was just stop using the list file and used another one and then revert to the original one and the original one suddenly works for install) I still have the same error with update.

so what was wrong previously? why did I receive error now?


open a terminal and type:

sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com 16126D3A3E5C1192

i.e. paste using SHIFT + INS the number you have copied - 16126D3A3E5C1192

You'll have to enter your password, the key will be downloaded and integrated.

  • can you explain this a little bit more? – Junchao Gu Jan 17 '14 at 7:47
  • 2
    I have been using Ubuntu for years, and I have never had to manually install signing keys in order to run apt-get update. Also the error message is not indicating that the public key is missing but rather that the signature is bad. – kasperd Oct 4 '14 at 8:12

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