> ## Documentation Index
> Fetch the complete documentation index at: https://docs.domino.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# 415 Unsupported Media Type Error When Calling the Domino REST API

> A 415 Unsupported Media Type error from the Domino REST API is caused by a missing or incorrect Content-Type header. Add Content-Type: application/json to your request headers to resolve.

### **Version/Environment (if relevant):**

All Domino Versions

## **Issue:**

A user receives a **415 Unsupported Media Type** error when calling the Domino REST API.

## **Root Cause:**

The API request is missing the Content-Type header, or it is set to an unsupported value. The Domino REST API requires requests to specify application/json as the content type.

## **Resolution:**

Add the Content-Type header to your API request:

```
Content-Type': 'application/json'
```

Since the header should also include your API key, the full header section will look like this:

```
headers = {
'Content-Type': 'application/json',
'X-Domino-Api-Key': '<api key>'
}
```

If you continue to experience issues, use [Postman](https://www.postman.com/) to test your API calls. Postman is a free application that allows you to test different media types and headers with minimal overhead.

Additional API examples can be found here: [API Examples for Domino's 5.x REST API](https://support.domino.ai/support/s/article/API-Examples-for-Domino-s-5-x-REST-API-1718868032320).

### **Notes/Information:**


## Related topics

- [Troubleshooting](/knowledge-base/troubleshooting-overview.md)
- [Returns the contents of a file](/api-reference/projects/returns-the-contents-of-a-file.md)
- [Returns the contents of a file (deprecated, use v1 endpoint instead)](/api-reference/projects/returns-the-contents-of-a-file-deprecated-use-v1-endpoint-instead.md)
- [Check whether Slurm submission is supported](/api-reference/hpc-jobs/check-whether-slurm-submission-is-supported.md)