Limits and refusals#

Every ceiling in one place, and what every refusal message means.

Use it to

see every ceiling, from one event up to the whole region
read a refusal message and know what it means
tell a stopped event from a stopped script

Nothing here crashes a script. A verb that cannot do what you asked answers nil and a reason in plain words, and your script carries on.

Luau

local ok, why = self:move_to(0, 5, 0)if not ok then    print("could not move: " .. why)end

Ceilings#

Per slice#

A slice is one event firing, or the script being loaded.

Limit	Value
Instruction units	50,000
World effects	8
Events sent (`emit` + `send`)	16
`print` lines	32
Length of one `print` line	512 bytes

A world effect is anything that changes the world: a move, a rotation, a tween, a spawn, a property write, a sound, a terrain stroke, a block edit, damage. Reads are free. raycast, players:list, world:clock, self:get and the whole of vec cost nothing.

Per script#

Limit	Value
Memory	4 MB
Keys in one `self:set`	32
Animation layers	8
Locomotion overrides	16

Per object#

Limit	Value
Scripts	8
Tags	16
Store keys	256
Store key length	256 bytes
Store value size	64 KB
Store total	1 MB

A personal HUD is tighter, because its memory lives on the central server for everyone, forever:

Limit	Value
Store keys	64
Store value size	8 KB
Store total	32 KB
All your HUDs together	1 MB

Per player, per world#

What one person keeps in a world is players.store. It lives on the central server and follows them between machines:

Limit	Value
Store keys	128
Store key length	256 bytes
Store value size	64 KB
Store total	256 KB
All the worlds you have played, together	16 MB

The region's own memory#

The region's shared memory, world.store, is one drawer for the whole world, not one per object:

Limit	Value
Store keys	4096
Store key length	256 bytes
Store value size	64 KB
Store total	8 MB

The loading screen#

What world.loading accepts. Past any of these the call is refused with a reason, not silently trimmed, because a screen that quietly dropped four of your twelve tips is a bug you would hunt in the wrong place.

Limit	Value
Headline	80 characters
Subtitle	160 characters
Tips	8
One tip	160 characters
Tip dwell	2 to 30 seconds
Background / logo, longest side	4096 px

Per region#

Limit	Value
Active scripts	768
Script-made objects alive at once	256
Named actions	32
Objects one `tagged` query may return	256
Pieces in a copied group	64

http#

What one world may send outside. The request count is generous because requests are cheap; the ceiling that actually binds is in bytes, because bandwidth is what costs.

Limit	Value
Requests a second	10, banking up to 60
Bytes a second	512 KB, banking up to 16 MB
Bytes a day	5 GB
Requests in the air, per script	8
Requests in the air, per world	64
Requests waiting for a slot	64
Body sent	64 KB
Answer accepted	256 KB
Time before it gives up	10 s (5 s to connect)
Headers	16, up to 1 KB each and 4 KB in total
URL	2 KB

The per-second budgets bank quiet time. A world that has been idle for a minute can fire all 60 at once, which is what makes forty players arriving together work, and then settles back to 10 a second.

A destination that fails 5 times in a row is left alone for 30 seconds, and calls to it answer http cooling immediately. A 404 is not a failure.

HUD stages#

A stage is a live 3D render every frame, the most expensive thing a HUD can hold, by a wide margin.

Limit	Value
Stages in one HUD	4
Pieces on one stage	64
Parts in a set on the shelf	256

Over either of the first two, the HUD is refused with a reason. A menu backdrop is dozens of pieces, not a city.

A set counts as the one piece you wrote, however many parts it brings. The ceiling on those is the shelf's own, applied when you publish it.

Ranges#

Thing	Range
Coordinates	±100 km
Scale	0.01 to 10,000
Velocity and push	up to 100 m/s
Tween length	0.05 to 600 s
Region radius	0.5 to 96 m
Raycast reach	up to 512 m
Spawn life	default 30 s, max 300 s (`0` = while the region runs)
Rate of fire and cycle	0.05 to 5 s
Light radius	0 to 96 m
Sound volume	0 to 4
Sound pitch	0.25 to 4
Wind	up to 40 m/s
Terrain brush radius	0.5 to 64 m
Terrain brush strength	0 to 8 m
Animation speed	−8 to 8
Event payload	3 levels deep, 32 entries, 512-byte strings
Channel name	1 to 64 characters

What stops a script#

Two very different outcomes.

The event is abandoned, the script lives#

An ordinary mistake, such as indexing something that is nil, calling a method that does not exist, arithmetic on text. The error is written to your console and the next event runs normally.

The script is killed#

Message	Meaning
`script budget exceeded`	one slice used more than 50,000 instruction units
`script memory limit exceeded`	the script went over 4 MB

It does not run again until you save it. Both mean the same thing in practice: a loop without an exit. Use a timer instead. A slice may not take long, but you may have as many slices as you like.

Refusal reasons#

Anywhere#

Reason	What happened
`permission`	this world, or this player, has not granted what the verb needs. See Permissions
`too many commands`	more than 8 world effects in one event
`too many moves`	the same, from a movement verb
`read-only key`	that property is not writable by scripts. See the list

Moving and physics#

Reason	What happened
`not dynamic`	`push` or `set_velocity` on an object that is not a physics body. Set `dynamic = true` first
`unknown part`	that part was deleted, or never existed
`look_at: target is not a direction`	the target is directly above, directly below, or the object's own position

Memory#

Reason	What happened
`store full`	the key ceiling is reached (256 per object, 4096 for the world). Existing keys still read, overwrite and delete
`value too large`	over 64 KB (8 KB on a HUD)

Carrying#

Reason	What happened
`permission`	that player has not interacted with this object
`socket`	no attachment point by that name. See Sockets
`child`	hold the root of a group, not one of its pieces
`held`	somebody else has it
`full`	their hands are full
`not held`	`drop` on something nobody was carrying

Making things#

Reason	What happened
`too many spawned objects`	the region already has 256 script-made objects alive
a spawn is made of one thing	you named more than one of `shape`, `model`, `copy`

Damage#

Reason	What happened
`this object has no max_health — it cannot be damaged`	set `max_health` first. This is how a world says what is breakable

Terrain and blocks#

Reason	What happened
`invalid brush`	radius or strength outside the allowed range
`invalid position`	outside the world
`box too big`	a `fill` covering too many cells. Refused whole, and said now rather than half-done later

Modules#

Reason	What happened
`unknown module '…'`	built-ins are `self`, `events`, `players`, `vec`, `world`, `objects`. For your own module, attach a sibling script with that name, or put it on the object named Modules and require `@modules/<name>` (Sharing code)
`cyclic require of module '…'`	two of your modules require each other

Reading a refusal#

Three shapes, and they mean different things: