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14

This question already has an answer here:

When I run the command:

sudo apt-get update

I got this following warning: 

There is no public key available for the following key IDs: 1397BC53640DB551

This is the only warning I got and I do not get any Error.

How I can fix it and what the key 1397BC53640DB551 is all about?

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marked as duplicate by David Foerster, Luís de Sousa, Eric Carvalho, Seth♦ May 12 '16 at 18:06

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.
1  
For reviewers: There are already 2 votes on askubuntu.com/questions/766205/… being a duplicate of this one. Let's not create a loop! – guntbert May 5 '16 at 18:40
    
Can you please include the full output of apt-get update in your question? – David Foerster May 6 '16 at 13:19
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You can check this SO thread for solution. Link to related site – Aniket Thakur Nov 1 '16 at 9:09
up vote 142 down vote accepted

I resolved running:

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 1397BC53640DB551

The command above download the missing key using the hexadecimal numbers given in the error (1397BC53640DB551) with apt-key. After running apt-key to download the missing PUBKEY, any packages from that repositories will be considered trusted.

It seems to be a known problem in chromium that is being worked on (check here). They are working to remove SHA1 encryption (link).

Another possible workarounds that have been posted on reddit

wget -q -O - https://dl.google.com/linux/linux_signing_key.pub | sudo apt-key add -

Looking at this, seems that Google now has two keys, and the old one will probably be discontinued along with SHA1.

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2  
The first one timed out for me (keyserver.ubuntu.com) so I had to use the second one from Google. – Ryan H. Sep 4 '16 at 17:42
    
If you're in an IPv6 only server, you can use pool.sks-keyservers.net instead of keyserver.ubuntu.com – James Z Aug 28 '17 at 18:11
up vote 41 down vote

Correct command line is:

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 1397BC53640DB551
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