I'm getting this error when running apt update (as root):

Get:13 https://armbian.hosthatch.com/apt buster/main armhf Packages [592 kB]                               
Err:13 https://armbian.hosthatch.com/apt buster/main armhf Packages                                 
 
Ign:15 https://us.mirrors.fossho.st/armbian/apt buster/main armhf Contents (deb)                           
Fetched 718 kB in 18s (40.9 kB/s)                                                                          
Reading package lists... Done
E: Failed to fetch https://armbian.hosthatch.com/apt/dists/buster/main/binary-armhf/Packages.gz  
E: Failed to fetch https://armbian.tnahosting.net/apt/dists/buster/buster-desktop/Contents-armhf.gz  Hash Sum mismatch
   Hashes of expected file:
    - Filesize:96109 [weak]
    - SHA512:85a1dd0e1f1a8717d19b27f557d43a52d66684e2de10136938a14db8c3885e045d4b3844b3e3cca6054374c543237111a950d5d9a73ee5949f90e0db14bc88f6
    - SHA256:77d0e508761d7498af6dd22e8187455ad817987dc556cdb3a98620290a6fb85e
    - SHA1:315817cdcdf715e2975a7b17a7ae48908fd753d7 [weak]
    - MD5Sum:1b9b596862c66cc1bc43efe3247c3850 [weak]
   Hashes of received file:
    - SHA512:eaf8261721500c8bf2060cd5e1b4dc3a8ba2db113d0752491b75c50f30e8292faa705cf1d07c25c38be5462eccaf5ad40b0581e9d8cd1845d24be6ef7e61f9f5
    - SHA256:8d69eb084de8f77619f25b57597c496de97b326881a3b1ba97b0f3eefc314734
    - SHA1:ddc15dfea93fe6db51059b991a7a7523120a6b96 [weak]
    - MD5Sum:f9f5009580fae5763565b687213efff6 [weak]
    - Filesize:96109 [weak]
   Last modification reported: Fri, 20 Nov 2020 10:41:49 +0000
   Release file created at: Tue, 01 Dec 2020 20:39:06 +0000
E: Some index files failed to download. They have been ignored, or old ones used instead.

 

I trimmed the beginning a bit, but I'm pretty sure I left enough context.

 

Does some package source need to re-issue their signatures? Is anyone else having this problem?

There are issues with mirror sync I think. I solved it by issuing apt update multiple times and a proper mirror was selected.

 

Like this?

until apt update;
do sleep 90;
done

 

Not that extreme, took me three retries I think. But I guess your way would work too