> For the complete documentation index, see [llms.txt](https://docs.console.zenlayer.com/api-reference/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.console.zenlayer.com/api-reference/zec/instance/resetinstances.md).
# ResetInstances
## 1. API Description
This API (ResetInstances) is used to reinstalls the operating system on one or more elastic compute instances. You can specify a new image, login method (password or key pair), time zone, and instance name.
#### Preparations
* Query images: you can call [DescribeImages](/api-reference/zec/image/describeimages.md) to query the information of the operating system image to be reinstalled.
{% hint style="info" %}
**Notes**
* Batch reinstallation processes each instance independently, so a partial failure does not affect the remaining ones. The failed items are returned through the `instanceIds` in the response.
* If the `imageId` parameter is specified, the specified image is used for the reinstallation. Otherwise, the reinstallation is performed with the image currently used by the instance.
* Reinstallation across operating system types (`osType`) is not supported. For example, `linux` cannot be reinstalled as `windows`.
* The system disk size of the instance must be greater than or equal to the size of the image to be reinstalled. Otherwise, the operation is rejected.
* The system disk is formatted and reset. Make sure that there is no important file on the system disk.
* Either a password or a keyPair must be specified, and only one of them can be specified.
* The operating system can be reinstalled only when the instance is shut down.
* `Windows` and `Generic` do not support specifying `key_id` for SSH login.
* After the reinstallation, the instance enters the `DEPLOYING` status. If the latest status of the instance changes to `RUNNING`, the operation succeeded. If it changes to `REINSTALL_FAILED`, the operation failed and you need to contact the administrator. The instance status can be queried by calling the [DescribeInstancesStatus](/api-reference/zec/instance/describeinstancesstatus.md) interface.
{% endhint %}
## 2. Input Parameters
The following request parameter list only provides API request parameters.
| Parameter Name | Required | Type | Description |
| -------------- | -------- | --------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| instanceIds | Yes | Array of String | ID of the instance to be reinstalled.
It can be obtained by calling DescribeInstances.
|
| password | No | String | New password of the instance.
Specify either this parameter or keyId (a password and a key cannot be specified for Windows and Generic images).
It must contain all of the following three types of characters: uppercase and lowercase letters (a-z, A-Z), digits (0-9), and special characters (\~!@$^\*-\_=+).
|
| keyId | No | String | Key ID.
Specify either this parameter or password (a password and a key cannot be specified for Windows and Generic images).
You can call DescribeKeyPairs to obtain the latest key pair information.
After a key is associated, you can access the instance with the corresponding private key. A key and a password cannot be specified at the same time, and the Windows operating system does not support specifying a key.
Example value: key-YWD2QFOl.
|
| imageId | No | String | Specify the image ID for the reinstallation.
It can be obtained from the imageId field returned by calling DescribeImages.
If it is not specified, the reinstallation is performed based on the current image.
|
| timezone | No | String | Time zone configuration for the operating system. |
| enableAgent | No | Boolean | Whether to enable the QEMU Guest Agent (QGA).
Default value: false
|
| instanceName | No | String | The modified instance name.
2 to 63 characters in length.
Only letters, digits, periods (.), underscores (\_), slashes (/) and hyphens (-) are supported, and it must start and end with a letter or a digit.
|
| userData | No | String | Custom initialization script for the instance. The value must be Base64-encoded, and the decoded size must be less than 64 KiB. |
## 3. Output Parameters
| Parameter Name | Type | Description |
| -------------- | --------------- | --------------------------------------------------------------------------------------------------------------------- |
| requestId | String | The unique request ID, which is returned for each request.
RequestId is required for locating a problem.
|
| instanceIds | Array of String | List of instance IDs for which the reinstallation operation failed. |
## 4. Code Example
{% tabs %}
{% tab title="Example" %}
**1. Reinstall the OS on multiple instances in a batch.**
```json
POST /api/v2/zec HTTP/1.1
Host: console.zenlayer.com
Content-Type: application/json
X-ZC-Action: ResetInstances
Request：
{
"instanceIds": ["" , ""],
"imageId": "ubuntu2022",
"password": "Example+123",
"enableAgent": true
}
Response：
{
"requestId": "T05992D0C-7E8B-4047-B0C0-780F2CD549D3",
"response": {
"instanceIds": [
"instanceId2"
],
"requestId": "T05992D0C-7E8B-4047-B0C0-780F2CD549D3"
}
}
```
**2. Reinstall the OS on multiple instances in a batch and specify an initialization script through `userData`. The `userData` in this example is the Base64-encoded value of the script `#!/bin/bash\necho "hello zenlayer" > /tmp/init.log`.**
```json
POST /api/v2/zec HTTP/1.1
Host: console.zenlayer.com
Content-Type: application/json
X-ZC-Action: ResetInstances
Request：
{
"instanceIds": ["" , ""],
"imageId": "ubuntu2022",
"password": "Example+123",
"enableAgent": true,
"userData": "IyEvYmluL2Jhc2gKZWNobyAiaGVsbG8gemVubGF5ZXIiID4gL3RtcC9pbml0LmxvZwo="
}
Response：
{
"requestId": "T05992D0C-7E8B-4047-B0C0-780F2CD549D3",
"response": {
"instanceIds": [
"instanceId2"
],
"requestId": "T05992D0C-7E8B-4047-B0C0-780F2CD549D3"
}
}
```
{% endtab %}
{% endtabs %}
## 5. Developer Resources
Zenlayer Cloud API 2.0 integrates [SDKs](/api-reference/api-introduction/toolkit/api-sdk.md)，to make it easier for you to call APIs. More programming languages will be supported.
## 6. Error Codes
The following only lists the error codes related to the API business logic. For other error codes, see [Common Error Codes](/api-reference/api-introduction/instruction/commonerrorcode.md).
| HTTP Status Code | Error Code | Description |
| ---------------- | ---------- | ----------- |