When I get asked if I want to ":: Import PGP key BC26F752D25B92CE272E0F44F7FD5492264BB9D0?" and answer with y, it tells me that it can not be looked up remotely and will fail to synchronise the repository.
Output:
[felix@fedora ~]$ sudo pacman -U devkitpro-keyring.pkg.tar.xz
loading packages...
warning: devkitpro-keyring-20180316-1 is up to date -- reinstalling
resolving dependencies...
looking for conflicting packages...
Packages (1) devkitpro-keyring-20180316-1
Total Installed Size: 0.03 MiB
Net Upgrade Size: 0.00 MiB
:: Proceed with installation? [Y/n] y
(1/1) checking keys in keyring [########################################################] 100%
(1/1) checking package integrity [########################################################] 100%
(1/1) loading package files [########################################################] 100%
(1/1) checking for file conflicts [########################################################] 100%
(1/1) checking available disk space [########################################################] 100%
:: Processing package changes...
(1/1) reinstalling devkitpro-keyring [########################################################] 100%
[felix@fedora ~]$ sudo pacman -Syu
:: Synchronizing package databases...
core is up to date
extra is up to date
:: Starting full system upgrade...
there is nothing to do
[felix@fedora ~]$ sudo nano /etc/pacman.conf
[felix@fedora ~]$ sudo pacman -Syu
error: dkp-libs: key "BC26F752D25B92CE272E0F44F7FD5492264BB9D0" is unknown
:: Import PGP key BC26F752D25B92CE272E0F44F7FD5492264BB9D0? [Y/n] y
error: key "BC26F752D25B92CE272E0F44F7FD5492264BB9D0" could not be looked up remotely
:: Synchronizing package databases...
core is up to date
extra is up to date
dkp-libs 141.9 KiB 1843 KiB/s 00:00 [########################################################] 100%
dkp-libs.sig 566.0 B 0.00 B/s 00:00 [########################################################] 100%
error: dkp-libs: key "BC26F752D25B92CE272E0F44F7FD5492264BB9D0" is unknown
:: Import PGP key BC26F752D25B92CE272E0F44F7FD5492264BB9D0? [Y/n] y
error: key "BC26F752D25B92CE272E0F44F7FD5492264BB9D0" could not be looked up remotely
error: failed to update dkp-libs (invalid or corrupted database (PGP signature))
error: failed to synchronize all databases