Hi!Can a runner access the upgrades in a central server?I know in the old rulebook said that he can but in the revised edition says that upgrades are accessible only in remote servers.Here is the copy+paste from the pdf "Accessing
The card, or cards, accessed from a successful run
depends on the server that was attacked.
R&D: The Runner accesses the top card of R&D.
When accessing multiple cards from R&D, those
cards are returned in their original order after all of
the cards have been accessed.
HQ: The Runner accesses one random card from
HQ. When accessing multiple cards from HQ, the
Runner does not return any of them to HQ until all
of the cards have been accessed.
Archives: The Runner flips all cards in the
Archives faceup. Then, the Runner accesses all cards
in the Archives in the order of their choosing.
Remote Server: The Runner accesses all asset,
agenda, and/or upgrade cards in the remote server.

Bold and underlined only in remote servers, thanks in advance!

You’re referencing the Learn to Play book, which is not comprehensive. The Rules Reference Guide is the authoritative document.

RRG p. 4 under Accessing :

Accessing Multiple Cards in a Server

When the Runner chooses to access cards in a server, they will access a set number of cards. Upon choosing to access, that number is determined by the total number of cards a successful run on that server would normally access, any active modifiers that may be adding to or reducing the number, plus all cards in a central server’s root.

So, nothing changed, you always* access upgrades no matter what server you’re running on.

*subject to modification by some card effects.