Used months-old ISO installer. Can't update: PGP corrupt

[anon89812132]

Yes, in general, if is about to do a fresh install is best to use the latest ISO.
Other than that, this should help:

[root tip] [How To] Mitigate and prevent GPGME error when syncing your system

You are getting a message when syncing your system error: GPGME error: No data error: failed to synchronize all databases (invalid or corrupted database (PGP signature)) Before you continue [SOLVED] Error updating system (error: GPGME error: No data) / Newbie Corner / Arch Linux Forums Pacman troubleshooting - Manjaro Pacman looking for database signature files Also see this pacman bugreport from 2015 - which was closed as not a bug but a matter of configuration. FS#44445 : "GPGME err…