Bless Spell and how it works for multi attacks

https://www.dndbeyond.com/spells/2618933-bless

Whenever a target makes an attack roll or a saving throw before the spell ends, the target adds 1d4 to the attack roll or save.

If I can multi attack.  I roll both the 1d4 and the 1d20 for each and every attack.

Yes.

Quote from Character77006 >>

https://www.dndbeyond.com/spells/2618933-bless

Whenever a target makes an attack roll or a saving throw before the spell ends, the target adds 1d4 to the attack roll or save.

 

If I can multi attack.  I roll both the 1d4 and the 1d20 for each and every attack.

"Whenever" means "whenever". If it were limited to once per turn, it would say "Once per turn, when a target makes an attack roll..."