Cannot upgrade on Ubuntu 20.04: Failed to fetch 404 Not Found

Seafile Client
#1

On my Ubuntu 20.04 machine, I cannot upgrade Seafile anymore. The output of sudo apt upgrade is:

The following packages will be upgraded:
  libseafile0 seafile-daemon seafile-gui
3 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Err:1 https://***/focal stable/main amd64 libseafile0 amd64 8.0.4

404 Not Found [IP: 3.86.184.216 443]

Err:2 https://***/focal stable/main amd64 seafile-daemon amd64 8.0.4

404 Not Found [IP: 3.86.184.216 443]

Err:3 https://***/focal stable/main amd64 seafile-gui amd64 8.0.4

404 Not Found [IP: 3.86.184.216 443]

**E:** Failed to fetch https://***/focal/pool/main/s/seafile-daemon/libseafile0_8.0.4_amd64.deb 404 Not Found [IP: 3.86.184.216 443]

**E:** Failed to fetch https://***/focal/pool/main/s/seafile-daemon/seafile-daemon_8.0.4_amd64.deb 404 Not Found [IP: 3.86.184.216 443]

**E:** Failed to fetch https://***/focal/pool/main/s/seafile-gui/seafile-gui_8.0.4_amd64.deb 404 Not Found [IP: 3.86.184.216 443]

**E:** Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?

Using sudo apt upgrade --fix-missing does not solve the issue.

Had to remove the URLs from the output because this forum disallows me to post “links”.