The Player's Handbook, pg. 114, once read (in the wizard's Spellcasting feature description):
The Wizard table shows how many spell slots you have to cast your spells of 1st level and higher.
The November 2018 PH errata states:
[New] Preparing and Casting Spells (p. 114). In the first sentence, “your spells” is now “your wizard spells.”
Now that section reads:
The Wizard table shows how many spell slots you have to cast your wizard spells of 1st level and higher.
The errata also applies the same change to classes and archetypes with the Spellcasting class feature.
A single-classed wizard won't notice the difference, but I wonder if this change means multiclassing means spell slots gained from multiclassing to cleric, for instance, cannot be used to cast wizard spells that is not in cleric spell list?
How does this errata change how multiclass spell slots work?
Best Answer
It doesn't
Multiclassing has its own set of rules that define what spell slots you have, and this overrides the spell slots mentioned in the wizard class section.
The errata you mention was added (I assume) to avoid you using those slots for spells gained from some other place such as a feat or racial feature.