Document file rules

Before storing a document, the Upload a document for an application endpoint validates the filename and file bytes. A failed check returns 400 with an errors array that names the failing field and error code. For upload steps, see Upload documents.

Read limits from the schema

Each file field can set its own types and size. Retrieve the application schema (GET /v1/onboarding/partner/applications/{applicationId}/schema) and read x-fileUpload on the target field:

"genericFileUploadBusinessRegistration": {
  "x-fileUpload": {
    "acceptedTypes": ["application/pdf", "image/jpeg", "image/png"],
    "maxSizeMb": 10
  }
}

If x-fileUpload is absent, the API uses the defaults in the following tables.

Filename

The API strips / and \ from fileName, then trims spaces at each end.

Rule	Value
Length	1 to 255 characters after path components are removed
Characters	Letters, numbers, spaces, hyphens (`-`), underscores (`_`), dots (`.`), commas (`,`), and parentheses (`()`)
Example	`Ownership Chart (1).pdf`, `Company, LLC.pdf`

Quotes, slashes, and other punctuation fail the character check.

File type

The API reads magic bytes in fileContent. It doesn’t trust the Content-Type header. Known signatures are PDF, JPEG, PNG, ZIP (Office Open XML), and OLE2 (legacy Office). A file with no matching signature returns unrecognized_type.

Source	Accepted types
Field `x-fileUpload.acceptedTypes`	The types listed on that field
No `x-fileUpload`	`application/pdf`, `image/jpeg`, `image/png`

Office files (DOC, XLS, DOCX, XLSX) pass only when the field schema lists those types. The default list doesn’t include them.

File size

Source	Limit
Field `x-fileUpload.maxSizeMb`	That value in megabytes
No `x-fileUpload`	10 MB

A file over the limit returns too_large.

Error codes

A failed check returns HTTP 400 with numeric code 181102. The body includes errors with field and code.

`field`	`code`	When
`fileName`	`required`	`fileName` is missing or blank
`fileName`	`too_long`	Name is longer than 255 characters
`fileName`	`invalid`	Name is empty after path components are removed
`fileName`	`invalid_characters`	Name has a character outside the allowlist
`fileContent`	`required`	`fileContent` is missing
`fileContent`	`empty`	File has zero bytes
`fileContent`	`unrecognized_type`	File bytes don’t match a known type
`fileContent`	`not_accepted`	Type isn’t in the field’s `x-fileUpload.acceptedTypes`
`fileContent`	`too_large`	File is larger than `x-fileUpload.maxSizeMb` (default 10 MB)

Mint

StableFX

Digital Asset Accounts

End User Onboarding

Read limits from the schema

Filename

File type

File size

Error codes

​Read limits from the schema

​Filename

​File type

​File size

​Error codes

Read limits from the schema

Filename

File type

File size

Error codes