Solution of apt unable to update in the docker container of raspberry pie

Today, apt failed to update when building the image with dockerfile on raspberry pie

...
 ---> Running in 05393fa6f242
Get:1 http://ports.ubuntu.com/ubuntu-ports focal InRelease [265 kB]
Get:2 http://ports.ubuntu.com/ubuntu-ports focal-updates InRelease [114 kB]
Err:1 http://ports.ubuntu.com/ubuntu-ports focal InRelease
  At least one invalid signature was encountered.
Err:2 http://ports.ubuntu.com/ubuntu-ports focal-updates InRelease
  At least one invalid signature was encountered.
Get:3 http://ports.ubuntu.com/ubuntu-ports focal-backports InRelease [101 kB]
Err:3 http://ports.ubuntu.com/ubuntu-ports focal-backports InRelease
  At least one invalid signature was encountered.
Get:4 http://ports.ubuntu.com/ubuntu-ports focal-security InRelease [114 kB]
Err:4 http://ports.ubuntu.com/ubuntu-ports focal-security InRelease
  At least one invalid signature was encountered.
Reading package lists...
W: GPG error: http://ports.ubuntu.com/ubuntu-ports focal InRelease: At least one invalid signature was encountered.
E: The repository 'http://ports.ubuntu.com/ubuntu-ports focal InRelease' is not signed.
W: GPG error: http://ports.ubuntu.com/ubuntu-ports focal-updates InRelease: At least one invalid signature was encountered.
E: The repository 'http://ports.ubuntu.com/ubuntu-ports focal-updates InRelease' is not signed.
W: GPG error: http://ports.ubuntu.com/ubuntu-ports focal-backports InRelease: At least one invalid signature was encountered.
E: The repository 'http://ports.ubuntu.com/ubuntu-ports focal-backports InRelease' is not signed.
W: GPG error: http://ports.ubuntu.com/ubuntu-ports focal-security InRelease: At least one invalid signature was encountered.
E: The repository 'http://ports.ubuntu.com/ubuntu-ports focal-security InRelease' is not signed.
...

The solution is:
in http://ftp.debian.org/debian/pool/main/libs/libseccomp/ Download the latest version of libseccomp2. The current version is libseccomp2_ 2.5.1-1_ Armhf. DEB
install on raspberry pie

>>> sudo dpkg -i libseccomp2_2.5.1-1_armhf.deb

“20999;” 21448;”

[br] https://askubuntu.com/a/1264921/685786
https://stackoverflow.com/a/64463211/7151777

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