# Update the desired machine version for an existing instance.

**PUT /machines/{machineSlug}/i/{instanceSlug}/v**

Set the desired machine version for an existing instance.

The instance will not be upgraded immediately but will be upgraded
the next time an event is sent to it from a settled state.

A 400 with code "no-migration-path" will be returned if there is
no path through the set of existing migrations from the current
instance version to the desired instance version.



## Servers
- Production server: https://api.statebacked.dev (Production server)


## Authentication methods
- Bearer auth


## Parameters

#### Path parameters
- **machineSlug** (string)
  The slug/name for the machine definition.
- **instanceSlug** (string)
  The slug/name for the machine instance.


## Body parameters
Content-type: 
Request to update the machine version for an existing instance.

- **targetMachineVersionId** (string)
  The ID of a machine definition version.

## Responses
### 201: The desired version was recorded successfully and will be applied
the next time an event is sent to the instance from a settled state.


### 400: The request was malformed.

#### Body Parameters:  (object)
- **error** (string)
  A description of the error.
- **code** (string)
  A code specifying the type of error.

- `specify-org` indicates that the user has access to multiple orgs and the operation requires specifying an organization. Pass the `x-statebacked-org-id` header to specify an org ID.
- `invalid-parameter` indicates that one of the provided parameters was incorrect

- **parameter** (string)
  The name of the invalid parameter

### 403: The request was unauthorized.

#### Body Parameters:  (object)
- **error** (string)
  A description of the error.
- **code** (string)
  A code specifying the type of error.


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