Both the Player's Handbook and Dungeon Master's Guide for the 2024 update of D&D 5th edition are now available and backward compatible with the rules published in 2014. (This was when the world was still young and I was playing The Lost Mines of Van der Vaart for the first time.) Wizards of the Coast has published a guide to updating campaigns to the new rules so that players can adapt to the changes.

Previous rule changes, such as the transition from AD&D 2nd edition to D&D 3.0's “Die Vecna Die!” module, some of which involved adventures that shook up the multiverse to illustrate, for example, that magic works in a completely different way. This is not a seismic shift. Instead, we get common sense advice about changing things incrementally, rather than all at once, and bullet points about notable rule changes.

Some of them deal with entirely new systems for crafting and weapon mastery, while others provide valuable lists of things you may not have noticed have changed. For example, the stunned state no longer reduces speed to zero, presumably to distinguish it from the extremely similar paralyzed state. When you are stunned, your concentration is broken, your actions are taken away, attacks against you are favored, and Strength and Dexterity saves automatically fail, but you can still move normally. This is a useful distinction and does not allow you to dash away because you lose action.

Grabs and thrusts used to require an Athletics check, but now are initiated by an unarmed blow. In my reading, this is a notable change. This is because it can now be initiated by an attack of opportunity, which was previously impossible under the rules as they were. When someone tries to run away from you, you have a chance to grab them instead of a chance to stab them.

Healing magic is more powerful, spells that restore hit points double the dice rolls, Cure wounds are now 2D8 per level, and spells like Aura of Vitality and Prayer of Healing have been powered up. Let's all thank the cleric.

Heroic Inspiration can be used to reroll any die; when it was called Inspiration, this mechanism gave advantage on attack dice, saving throws, and ability checks, but now it can be used on any die, including damage dice. It can be used after the fact on dice. Another difference with Heroic Inspiration, not mentioned in the guide, is that if it is acquired while you already have it, you can pass it on to another player instead of wasting it. This is a good thing.

And finally, it takes a bonus action to drink a potion. Previously, it required one action, which was so prohibitive that I and most other DMs I know (including Larian) excluded it in our house rules.

Of course, if you don't update to the latest rules, the rulebook police won't show up at your door, but if you want to keep up, some official guidance on changes would be helpful. Especially when it comes to changes that affect player builds; as WotC says, “Waiting until the current campaign is finished or the character's story is naturally complete before switching to a character built under the 2024 rules is perfectly No problem.”