Hash sum mismatch error while upgrading

Question

I'm using Pop_Os! 20.04. While trying to upgrade it i'm getting the following error :

sudo apt-get upgrade

Get:1 http://us.archive.ubuntu.com/ubuntu focal-updates/main amd64 apparmor amd64 

2.13.3-7ubuntu5.1 [494 kB]
Err:1 http://us.archive.ubuntu.com/ubuntu focal-updates/main amd64 apparmor amd64 2.13.3-7ubuntu5.1
  Hash Sum mismatch
  Hashes of expected file:
   - SHA256:6359c1166bdc8946d83d5ccf0a51d22d3e65698bcbfb407b8c51cb0cf0fa693b
   - SHA1:583e8718e1d7df0ac1cec1d172a00b5c1f3e068a [weak]
   - MD5Sum:c9472e4b9fed70d333a94abf4def982f [weak]
   - Filesize:494020 [weak]
  Hashes of received file:
   - SHA256:3e93ae0f10e6ad2f187e62d903692ea4d1df89aabbf0bc0b891f0ccb1a7a1f06
   - SHA1:2b2318c322cf63cf31a9a956b8e1fc4109c95071 [weak]
   - MD5Sum:16db382d293cd562a529fbcc52b69691 [weak]
   - Filesize:494020 [weak]
  Last modification reported: Fri, 22 May 2020 11:58:22 +0000
Fetched 494 kB in 1s (636 kB/s)  
E: Failed to fetch http://us.archive.ubuntu.com/ubuntu/pool/main/a/apparmor/apparmor_2.13.3-7ubuntu5.1_amd64.deb  Hash Sum mismatch
   Hashes of expected file:
    - SHA256:6359c1166bdc8946d83d5ccf0a51d22d3e65698bcbfb407b8c51cb0cf0fa693b
    - SHA1:583e8718e1d7df0ac1cec1d172a00b5c1f3e068a [weak]
    - MD5Sum:c9472e4b9fed70d333a94abf4def982f [weak]
    - Filesize:494020 [weak]
   Hashes of received file:
    - SHA256:3e93ae0f10e6ad2f187e62d903692ea4d1df89aabbf0bc0b891f0ccb1a7a1f06
    - SHA1:2b2318c322cf63cf31a9a956b8e1fc4109c95071 [weak]
    - MD5Sum:16db382d293cd562a529fbcc52b69691 [weak]
    - Filesize:494020 [weak]
   Last modification reported: Fri, 22 May 2020 11:58:22 +0000

I have looked at different solutions which try to fix it when this occurs during

sudo apt-get update

but my update command works fine.

Solutions i tried were removing the apt lists and updating it again. I also tried setting acquire-by-hash to yes but it didn't work either. I think the problem here is not the same.

Solution

The following steps might help solving the issue:

Refreshing the APT cache

sudo apt-get clean
sudo apt-get update

Refreshing the APT lists

sudo rm -R /var/lib/apt/lists/*
sudo apt-get update

Refreshing both

sudo apt-get clean
sudo rm -R /var/lib/apt/lists/*
sudo apt-get update

But in cases it might be simply a temporary issue with the used APT mirror, which means that you should take a coffee and retry a few hours or a night later, before investing too much time to investigate an issue which solves itself shortly after ;).

Comments

[mr_pool_404]

I guess the issue was with the mirror. I already tried the above solutions but it didn't work. But after some time it just magically started working ;)

[MichaIng]

Indeed not an uncommon issue. For a single user/system it happens rarely or never, but we maintain a distro based on Debian/Raspbian repo and get similar reports regularly.