title: Ubuntu cannot sudo apt-get update
body: <p>When I did sudo apt-get update , I got below error (I tried <a href="https://stackoverflow.com/questions/30316812/ubuntu-apt-get-unable-to-fetch-packages">Ubuntu apt-get unable to fetch packages</a>
  but not resolved)
  It seems like having two errors:</p>
  <p>error:1 <a href="http://us.archives.ubuntu.com/ubuntu" rel="nofollow noreferrer">http://us.archives.ubuntu.com/ubuntu</a> focal InRelease
  Could not resolve 'us.archives.ubuntu.com'</p>
  <p>error:2 <a href="http://us.archive.ubuntu.com/ubuntu" rel="nofollow noreferrer">http://us.archive.ubuntu.com/ubuntu</a> focal-updates InRelease<br />
  The following signatures were invalid: BADSIG 3B4FE6ACC0B21F32 Ubuntu Archive
  Automatic Signing Key (2012) ftpmaster@ubuntu.com</p>
  <pre><code>Err:1 http://us.archives.ubuntu.com/ubuntu focal InRelease
    Could not resolve 'us.archives.ubuntu.com'
  Get:2 http://us.archive.ubuntu.com/ubuntu focal-updates InRelease [114 kB]                                                 
  Get:3 http://us.archive.ubuntu.com/ubuntu focal-backports InRelease [101 kB]                                                                     
  Err:2 http://us.archive.ubuntu.com/ubuntu focal-updates InRelease                                           
    The following signatures were invalid: BADSIG 3B4FE6ACC0B21F32 Ubuntu Archive 
     Automatic Signing Key (2012) &lt;ftpmaster@ubuntu.com&gt;
  Get:4 http://ppa.launchpad.net/ondrej/php/ubuntu focal InRelease [23.9 kB]                                   
  Get:5 http://us.archive.ubuntu.com/ubuntu focal InRelease [265 kB]                                                     
  Get:6 http://us.archive.ubuntu.com/ubuntu focal-backports/main amd64 Packages [2,568 
    ........
   
    Hash Sum mismatch
    Hashes of expected file:
     - Filesize:10412 [weak]
     - SHA256:06a37de4712eb5db853fa1c663395c28f539e7fca07f8bde8f45b2224c3d2ed7
     - SHA1:89f3783fb783ede69e0d898f0bccd2ff2cd4f871 [weak]
     - MD5Sum:0e3b2d5be786692c296e818d613d8c97 [weak]
    Hashes of received file:
     - SHA256:1d92320261cff061bebf2abd1c5d2ad4f40623764b4fb7cce7928ebd073fe158
     - SHA1:73fc423211b9d2aecbd6b7994997d4b16de7599c [weak]
     - MD5Sum:c02c53e77e824664b0003871a79ae0ae [weak]
     - Filesize:10412 [weak]
    Last modification reported: Sun, 14 Nov 2021 20:49:23 +0000
    Release file created at: Sun, 14 Nov 2021 22:32:20 +0000
  Get:15 http://us.archive.ubuntu.com/ubuntu focal-backports/universe DEP-11 48x48 
   Icons [2,809 B]
  Err:5 http://us.archive.ubuntu.com/ubuntu focal InRelease                                          
    The following signatures were invalid: BADSIG 3B4FE6ACC0B21F32 Ubuntu Archive 
     Automatic Signing Key (2012) &lt;ftpmaster@ubuntu.com&gt;
  Get:16 http://us.archive.ubuntu.com/ubuntu focal-backports/universe DEP-11 64x64 
    Icons [5,607 B]
  Err:4 http://ppa.launchpad.net/ondrej/php/ubuntu focal InRelease                           
    The following signatures couldn't be verified because the public key is not 
     available: NO_PUBKEY 4F4EA0AAE5267A6C
  Get:17 http://us.archive.ubuntu.com/ubuntu focal-backports/universe DEP-11 64x64@2 
  Icons [29 B]
  Get:18 http://us.archive.ubuntu.com/ubuntu focal-backports/universe amd64 c-n-f 
  Metadata [580 B]
  Get:19 http://us.archive.ubuntu.com/ubuntu focal-backports/multiverse amd64 c-n-f 
  Metadata [116 B]
  Get:20 http://security.ubuntu.com/ubuntu focal-security InRelease [114 kB]                 
  Get:21 http://security.ubuntu.com/ubuntu focal-security/main i386 Packages [306 kB]
  Err:21 http://security.ubuntu.com/ubuntu focal-security/main i386 Packages
    Hash Sum mismatch
    Hashes of expected file:
     - Filesize:305872 [weak]
     - SHA256:a3efeb4965b7327463bcefc80a4f26e1c305fa6466a719fc4834cb94911c01bf
     - SHA1:05a201d620a273fc570f8238e28381ff44117137 [weak]
     - MD5Sum:d73456392d61f28971c7d0e58d6ee71f [weak]
    Hashes of received file:
     - SHA256:0351cb3ccb8a33c8cfd617919a015ef9764184e0dac4d7af54033de4edfe2ce3
     - SHA1:3b0d69aa8802e4a81624421c80819537264d5de6 [weak]
     - MD5Sum:0d44cff357ba3b77cd0109dff04b4407 [weak]
     - Filesize:305872 [weak]
    Last modification reported: Thu, 11 Nov 2021 21:59:55 +0000
    Release file created at: Sun, 14 Nov 2021 22:31:05 +0000
  Get:22 http://security.ubuntu.com/ubuntu focal-security/main amd64 Packages [987 kB]
  Err:22 http://security.ubuntu.com/ubuntu focal-security/main amd64 Packages
    
  Get:23 http://security.ubuntu.com/ubuntu focal-security/main Translation-en [183 kB]
  Err:23 http://security.ubuntu.com/ubuntu focal-security/main Translation-en
     
  </code></pre>