pacman安装ubuntu_用Pacman安装软件包

I have been using Ubuntu/Mint for some years now, but I'm new to Arch Linux and such. I tried installing Arch Linux using this guide and at the time of running pacstrap -i /mnt base I got an error such as

==> Creating install root at /mnt

==> Installing packages to /mnt

error: GPGME error: No data

error: GPGME error: No data

error: GPGME error: No data

:: Synchronizing package databases...

core 1545.0 B 0.00B/s 00:00 [################################################] 100%

core.sig 1545.0 B 0.00B/s 00:00 [################################################] 100%

error: GPGME error: No data

error: failed to update core (invalid or corrupted database (PGP signature))

extra 1545.0 B 0.00B/s 00:00 [################################################] 100%

extra.sig 1545.0 B 0.00B/s 00:00 [################################################] 100%

error: GPGME error: No data

error: failed to update extra (invalid or corrupted database (PGP signature))

community 1545.0 B 0.00B/s 00:00 [################################################] 100%

community.sig 1545.0 B 0.00B/s 00:00 [################################################] 100%

error: GPGME error: No data

error: failed to update community (invalid or corrupted database (PGP signature))

error: failed to synchronize any databases

error: failed to init transaction (invalid or corrupted database (PGP signature))

==> ERROR: Failed to install packages to new root

I took that as an inability of mine to install Arch Linux and tried to install Manjaro instead. It installed fine, but when I run, for example, pacman -Syu from Manjaro I get a similar error.

I did some digging (for example here) and I think that it's an issue with my ISP. To use the words another person used: I think my "ISP is filtering and redirecting pacman requests to it's own html redirection page".

问题是我无法从另一个ISP安装它。有什么办法解决吗？

P.S.: I've tried already pretty much everything on this page.

编辑

我尝试了几个不同的镜子，它们都给出了相同的结果。

I tried running pacman -S archlinux-keyring on Manjaro and this is the output:

error: GPGME error: No data

error: GPGME error: No data

error: database 'community' is not valid (invalid or corrupted database (PGP signature))

error: database 'multilib' is not valid (invalid or corrupted database (PGP signature))