Send this page to your frontend developer colleague

aka "how this project affects responses during project startup".

While the server is still starting - clients will receive:

503 Service Unavailable HTTP code.
Built-in and custom headers to detect the bootstrap state:
- Retry-After: 1 (only if server is still starting)
- X-Maintenance: true
- Cache-Control: no-cache
Custom JSON model that represents current status.

JSON model has a non-changing structure:

{
  "state": 0,
  "currentTask": null
}

Field	Description
`state`	(`number`) Current bootstrap state (described below).
`currentTask`	(`string or null`) Name of the current task server's running. Can be a humanized name or a localizable string. Depends on the usage. Will be `null` if current state isn't `InProgress`.

Available states:

Value	Name	Description
`0`	`InProgress`	Bootstrap is in progress. Retry request later.
`1`	`Successful`	Usually is not seen in the responses. May be seen in case of unfixed race condition.
`2`	`Error`	Error has occurred during bootstrap. This state is final and will not change.

02 November 2025