---
schema_version: "1"
id: 80501a86d211f97e25824ec19a4bf8d32532f2672582e60026ea4a975471f9d3
title: fail
collection: mulesoft
version: current
locale: en-us
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canonical_url: https://docs.mulesoft.com/dataweave/2.12/dw-runtime-functions-fail
source_site: docs.mulesoft.com
content_type: documentation
content_hash: 3d4d764504eae6a2fa593de4466bb41594dccfa484f21f8346fe604e4c8ae0a0
description: MuleSoft Documentation Site
release: "2.12"
latest: false
---
---
product: DataWeave
version: 2.12
---

# fail

> For the full documentation index, see: https://docs.mulesoft.com/llms.txt

## fail(message: String = 'Error'): Nothing

Throws an exception with the specified message.

### Parameters

<table><colgroup><col> <col></colgroup><thead><tr><th>Name</th><th>Description</th></tr></thead><tbody><tr><td><p><code>message</code></p></td><td><p>An error message (<code>String</code>).</p></td></tr></tbody></table>

### Example

This example returns a failure message `Data was empty` because the expression
`(sizeOf(myVar) <= 0)` is `true`. A shortened version of the error message is shown in the output.

#### Source

```DataWeave
%dw 2.0
import * from dw::Runtime
var result = []
output application/json
---
if(sizeOf(result) <= 0) fail('Data was empty') else result
```

#### Output

```TXT
ERROR 2018-07-29 11:47:44,983 ...
*********************************
Message               : "Data was empty
...
```