Errors

Typed validation errors raised while builders materialize or explicit payload validation runs. Every subclass includes a machine-readable category and a path identifying the invalid field.

ErrorCategory

type ErrorCategory = 
  | "length-exceeded"
  | "out-of-range"
  | "mutually-exclusive"
  | "type-mismatch"
  | "missing-required"
  | "invalid-usage";

Stable machine-readable category attached to every validation error.

---

InvalidUsageError

Base class for invalid Block Kit input.

Catch this class to handle every slackblocks validation failure, or catch a subclass when the reason matters to application behavior.

Extends

• Error

Extended by

• LengthError
• OutOfRangeError
• MutualExclusivityError
• TypeMismatchError
• MissingRequiredError

Constructors

Constructor

new InvalidUsageError(path, message): InvalidUsageError;

Creates a validation error.

Parameters

Parameter	Type	Description
path	string	Dot-and-index path to the invalid field.
message	string	Human-readable explanation of the constraint.

Returns

InvalidUsageError

Overrides

Error.constructor

Properties

Property	Modifier	Type	Default value	Description
category	readonly	ErrorCategory	"invalid-usage"	Machine-readable failure category.
path	readonly	string	undefined	Dot-and-index path to the invalid payload field.

---

LengthError

A string, array, or collection falls outside a field's allowed length. Typical causes include text exceeding Slack's limit, too many options, or an action identifier longer than 255 characters.

Extends

• InvalidUsageError

Constructors

Constructor

new LengthError(path, message): LengthError;

Creates a validation error.

Parameters

Parameter	Type	Description
path	string	Dot-and-index path to the invalid field.
message	string	Human-readable explanation of the constraint.

Returns

LengthError

Inherited from

InvalidUsageError.constructor

Properties

Property	Modifier	Type	Description	Overrides
category	readonly	"length-exceeded"	Machine-readable failure category.	InvalidUsageError.category
path	readonly	string	Dot-and-index path to the invalid payload field.	-

---

MissingRequiredError

A required field or one-of requirement is not satisfied. Typical causes include building a section without text or fields, or creating a conversation filter without any filter options.

Extends

• InvalidUsageError

Constructors

Constructor

new MissingRequiredError(path, message): MissingRequiredError;

Creates a validation error.

Parameters

Parameter	Type	Description
path	string	Dot-and-index path to the invalid field.
message	string	Human-readable explanation of the constraint.

Returns

MissingRequiredError

Inherited from

InvalidUsageError.constructor

Properties

Property	Modifier	Type	Description	Overrides
category	readonly	"missing-required"	Machine-readable failure category.	InvalidUsageError.category
path	readonly	string	Dot-and-index path to the invalid payload field.	-

---

MutualExclusivityError

Mutually exclusive fields are supplied together. Examples include combining an image URL with a Slack file, or providing both options and option groups to a static select menu.

Extends

• InvalidUsageError

Constructors

Constructor

new MutualExclusivityError(path, message): MutualExclusivityError;

Creates a validation error.

Parameters

Parameter	Type	Description
path	string	Dot-and-index path to the invalid field.
message	string	Human-readable explanation of the constraint.

Returns

MutualExclusivityError

Inherited from

InvalidUsageError.constructor

Properties

Property	Modifier	Type	Description	Overrides
category	readonly	"mutually-exclusive"	Machine-readable failure category.	InvalidUsageError.category
path	readonly	string	Dot-and-index path to the invalid payload field.	-

---

OutOfRangeError

A numeric value falls outside a field's allowed range. Typical causes include minimum values greater than maximum values or counts outside Slack's supported bounds.

Extends

• InvalidUsageError

Constructors

Constructor

new OutOfRangeError(path, message): OutOfRangeError;

Creates a validation error.

Parameters

Parameter	Type	Description
path	string	Dot-and-index path to the invalid field.
message	string	Human-readable explanation of the constraint.

Returns

OutOfRangeError

Inherited from

InvalidUsageError.constructor

Properties

Property	Modifier	Type	Description	Overrides
category	readonly	"out-of-range"	Machine-readable failure category.	InvalidUsageError.category
path	readonly	string	Dot-and-index path to the invalid payload field.	-

---

TypeMismatchError

A payload field or nested object has the wrong runtime type or an unsupported discrete value. The error path identifies the exact field that failed runtime validation.

Extends

• InvalidUsageError

Constructors

Constructor

new TypeMismatchError(path, message): TypeMismatchError;

Creates a validation error.

Parameters

Parameter	Type	Description
path	string	Dot-and-index path to the invalid field.
message	string	Human-readable explanation of the constraint.

Returns

TypeMismatchError

Inherited from

InvalidUsageError.constructor

Properties

Property	Modifier	Type	Description	Overrides
category	readonly	"type-mismatch"	Machine-readable failure category.	InvalidUsageError.category
path	readonly	string	Dot-and-index path to the invalid payload field.	-