No, spells cast from spell scrolls do not require Somatic components (or indeed any components beyond what is specified in the spell scroll magic item)
The most general rule of D&D is the Specific vs General Rule:
This compendium contains rules that govern how the game plays. That said, many racial traits, class features, spells, magic items, monster abilities, and other game elements break the general rules in some way, creating an exception to how the rest of the game works. Remember this: If a specific rule contradicts a general rule, the specific rule wins.
General rules govern each part of the game. For example, the combat rules tell you that melee weapon attacks use Strength and ranged weapon attacks use Dexterity. That’s a general rule, and a general rule is in effect as long as something in the game doesn’t explicitly say otherwise.
The game also includes elements — class features, spells, magic items, monster abilities, and the like — that sometimes contradict a general rule. When an exception and a general rule disagree, the exception wins. For example, if a feature says you can make melee weapon attacks using your Charisma, you can do so, even though that statement disagrees with the general rule.
(Xanathar's Guide to Everything Introduction)
It's so important they said it twice! Reading these two sets of rules text it is clear, and exception to a rule must be:
- Explicit not implicit
With that in mind, we are going to examine the rules for using a spell scroll, from the most general (casting a spell from a magic item), through the rules for the specific type of magic items (scrolls), to the rules for the specific item in question (a spell scroll).
Casting a spell from a Magic Item
The DMG section on spells cast from magic items has this to say (emphasis mine):
Activating some magic items requires a user to do something in particular, such as holding the item and uttering a command word, reading the item if it is a scroll, or drinking it if it is a potion. The description of each item category or individual item details how an item is activated. Certain items use one or more of the following rules related to their activation.
Some magic items allow the user to cast a spell from the item, often by expending charges from it. The spell is cast at the lowest possible spell and caster level, doesn't expend any of the user's spell slots, and requires no components unless the item's description says otherwise. The spell uses its normal casting time, range, and duration, and the user of the item must concentrate if the spell requires concentration. Certain items make exceptions to these rules, changing the casting time, duration, or other parts of a spell.
(DMG > Treasure > Magic Items > Activating an Item)
Spells cast from spell scrolls thus must start from this default position, unless the description of either magic item scrolls or spell scrolls adds back in component requirements. This requirement is a specific, additive requirement. It also agrees with the principle of there are no Hidden Rules that guides 5e design. In order for something to be a rule, it needs to be written down.
Magic Item Category: Scroll
The description of scrolls from the DMG, is more specific, and applies to all scrolls. It states:
Most scrolls are spells stored in written form, while a few bear unique incantations that produce potent wards. Whatever its contents, a scroll is a roll of paper, sometimes attached to wooden rods, and typically kept safe in a tube of ivory, jade, leather, metal, or wood.
A scroll is a consumable magic item. Whatever the nature of the magic contained in a scroll, unleashing that magic requires the user to read the scroll. When its magic has been invoked, the scroll can’t be used again. Its words fade, or it crumbles into dust.
Unless a scroll's description says otherwise, any creature that can understand a written language can read the script on a scroll and attempt to activate it.
(DMG > Treasure > Magic Items > Magic Item Categories)
So, scrolls require the user to read a scroll (although it's not clear if this reading is out loud or not). This is an additional requirement for scrolls in order to "[unleash it's] magic". You might even call it a component!
Now in order to read the scroll, you must have it open and be able to see the text, as you need to be able to see text in order to read it. This doesn't, however, mean you need to hold a scroll to read it.
The game provides optional rules in the DMG for restricting reading and writing:
[...] In a region where one race has subjugated another, the language of the conquerors can become a mark of social status. Similarly, reading and writing might be restricted by law to the upper classes of a society.
(DMG > A Wold of Your Own > Languages and Dialects)
Since this is an optional restriction, we must conclude that unless otherwise specified, if you can understand a language, you can also read that language (in general).
Thus we can conclude two things:
- Once you understand the language you can read it
- In order to read it you don't need to speak it (as even someone unable to speak can still read, ala the Kenku)
Specific Magic Item: Spell Scroll
Now we drill down to the most specific subset, the spell scroll specific rules (emphasis mine):
A spell scroll bears the words of a single spell, written in a mystical cipher. If the spell is on your class’s spell list, you can read the scroll and cast its spell without providing any material components. Otherwise, the scroll is unintelligible. Casting the spell by reading the scroll requires the spell’s normal casting time. Once the spell is cast, the words on the scroll fade, and it crumbles to dust. If the casting is interrupted, the scroll is not lost.
(DMG > Treasure > Magic Items > Magic Items A - Z)
This description doesn't add back in any of the spell components (as would be required from the general magic item rule on spells, or indeed for an exception to exist).
It also reiterates the need to read the scroll, and emphasises that the casting of the spell via reading must use the spell's normal casting time. It does limit who can read the scroll however to only be spellcasters with the spell on their spell list.
Thus, the spell scroll requires no components to cast the spell beyond the act of reading the scroll over the period of the spell's normal casting time.
As a result it does not require Somatic components, or indeed Verbal or Material components either.
But what about the Intent of the Errata Change?
As an aside on what was intended, or not, by an errata update, we can use WoTC's official outlet for Rules As Intended (RAI), the Sage Advice Compendium, which states:
Which is correct in the Dungeon Master’s Guide, the rule for scrolls or the rule for a spell scroll?
They’re both correct. The rule for scrolls (p. 139) is for scrolls in general, including a scroll of protection, and it allows you to try to activate a spell if you’re literate. The rule for a spell scroll is specific to that type of scroll and introduces an additional requirement: the spell on the scroll must be on your class’s spell list for you to read the scroll.
[...]. No matter how its name appears, a spell scroll follows the same rule.
The intent behind the spell scroll rule, and the exception it is meant to provide over and above the other two general rules is clearly laid out in this SAC Q&A (emphasis mine):
The rule for scrolls (p. 139) is for scrolls in general, including a scroll of protection, and it allows you to try to activate a spell if you’re literate. The rule for a spell scroll is specific to that type of scroll and introduces an additional requirement: the spell on the scroll must be on your class’s spell list for you to read the scroll.
The intention is that the additional requirement the spell scroll rules adds is that to use a spell scroll the spell contained on it must be on your spellcasting spell list.
It doesn't remove any other restrictions, nor does it add any hidden restrictions requiring obtuse logic to work out the intention (eg the fact verbal and somatic components aren't called out in the most specific rule as being not required in means that they are required, even though the more general rule for the magic item says no spell components are required).
If further evidence for the intent behind what that rule means, we have this exchange between Jeremy Crawford and a querant on twitter:
@DakotaHansen13 · Apr 24, 2018
@JeremyECrawford Casting from a spell scroll. It doesn't say it requires V/S components, but specifically lists not using M. Does that line override the general rule about not needing V/S/M for any spells from magic items, so you would need V/S?
@JeremyECrawford · Apr 24, 2018
Spell scrolls follow the normal rule for casting a spell from a magic item: you don't need to provide any components to cast the spell (V, S, or M). Spell scrolls have a twist, though: you must read the scroll to cast its spell. This is effectively an ad hoc component. #DnD
While this is not an official source of rules, it is an interpretation provided by the main rules designer, and can be used to reinforce a RAI interpretation. It also happens to agree with the RAW interpretation I have provided here.