> For the complete documentation index, see [llms.txt](https://boxlang.ortusbooks.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://boxlang.ortusbooks.com/boxlang-language/reference/built-in-functions/system/throw.md).

# Throw

Throws a developer-specified exception, which can be caught with a catch block.

## Method Signature

```
Throw(message=[any], type=[String], detail=[String], errorcode=[String], extendedinfo=[any], object=[Throwable])
```

### Arguments

| Argument       | Type        | Required | Description                                                                                                                                                                                                            | Default |
| -------------- | ----------- | -------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------- |
| `message`      | `any`       | `false`  | Message that describes exception event                                                                                                                                                                                 |         |
| `type`         | `String`    | `false`  | The type of the exception                                                                                                                                                                                              |         |
| `detail`       | `String`    | `false`  | Description of the event                                                                                                                                                                                               |         |
| `errorcode`    | `String`    | `false`  | A custom error code that you supply                                                                                                                                                                                    |         |
| `extendedinfo` | `any`       | `false`  | Additional custom error data that you supply                                                                                                                                                                           |         |
| `object`       | `Throwable` | `false`  | <p>An instance of an exception object. If there is no message provided, this object will be thrown directly. If there is a message, a<br>CustomException will be thrown and this object will be used as the cause.</p> |         |

## Examples

### Throw a custom exception

Use the throw function to throw a custom application exception.

```java
<bx:script>
	throw( type="MyCustomError", message="A custom error has been thrown!" );
</bx:script>

```

### Throw a custom http response exception

Use the throw function to throw a custom exception when the http response is invalid.

```java
if( !isJSON( httpResponse.FILECONTENT ) ) {
	throw( type="InvalidHTTPResponse", message="The http response was not valid JSON" );
}

```

### Additional Examples

```java
// thrown as a statement example
try {
	throw "thrown";
} catch ( e) {
	dump( var=bxcatch, label="single argument keyword" );
}

try {
	throw message = "thrown";
	detail = "deets";
	errorCode = "403";
	type = "Test";
} catch ( e) {
	dump( var=bxcatch, label="additional arguments are ignored" );
}
// use this syntax instead
try {
	throw( message="thrown", detail="deets", errorCode="403", type="Test" );
} catch ( e) {
	dump( var=bxcatch, label="script throw with arguments" );
}

```

## Related

* [ApplicationRestart](/boxlang-language/reference/built-in-functions/system/applicationrestart.md)
* [ApplicationStartTime](/boxlang-language/reference/built-in-functions/system/applicationstarttime.md)
* [ApplicationStop](/boxlang-language/reference/built-in-functions/system/applicationstop.md)
* [BoxAnnounce](/boxlang-language/reference/built-in-functions/system/boxannounce.md)
* [BoxAnnounceAsync](/boxlang-language/reference/built-in-functions/system/boxannounceasync.md)
* [BoxAST](/boxlang-language/reference/built-in-functions/system/boxast.md)
* [BoxModuleReload](/boxlang-language/reference/built-in-functions/system/boxmodulereload.md)
* [BoxRegisterInterceptionPoints](/boxlang-language/reference/built-in-functions/system/boxregisterinterceptionpoints.md)
* [BoxRegisterInterceptor](/boxlang-language/reference/built-in-functions/system/boxregisterinterceptor.md)
* [BoxRegisterRequestInterceptor](/boxlang-language/reference/built-in-functions/system/boxregisterrequestinterceptor.md)
* [BoxUnregisterInterceptor](/boxlang-language/reference/built-in-functions/system/boxunregisterinterceptor.md)
* [BoxUnregisterRequestInterceptor](/boxlang-language/reference/built-in-functions/system/boxunregisterrequestinterceptor.md)
* [CallStackGet](/boxlang-language/reference/built-in-functions/system/callstackget.md)
* [CreateGUID](/boxlang-language/reference/built-in-functions/system/createguid.md)
* [CreateObject](/boxlang-language/reference/built-in-functions/system/createobject.md)
* [CreateUUID](/boxlang-language/reference/built-in-functions/system/createuuid.md)
* [DE](/boxlang-language/reference/built-in-functions/system/de.md)
* [DebugBoxContexts](/boxlang-language/reference/built-in-functions/system/debugboxcontexts.md)
* [Dump](/boxlang-language/reference/built-in-functions/system/dump.md)
* [Duplicate](/boxlang-language/reference/built-in-functions/system/duplicate.md)
* [echo](/boxlang-language/reference/built-in-functions/system/echo.md)
* [EncodeForHTML](/boxlang-language/reference/built-in-functions/system/encodeforhtml.md)
* [GetApplicationMetadata](/boxlang-language/reference/built-in-functions/system/getapplicationmetadata.md)
* [GetBaseTagData](/boxlang-language/reference/built-in-functions/system/getbasetagdata.md)
* [GetBaseTagList](/boxlang-language/reference/built-in-functions/system/getbasetaglist.md)
* [GetBaseTemplatePath](/boxlang-language/reference/built-in-functions/system/getbasetemplatepath.md)
* [GetBoxContext](/boxlang-language/reference/built-in-functions/system/getboxcontext.md)
* [GetBoxRuntime](/boxlang-language/reference/built-in-functions/system/getboxruntime.md)
* [GetBoxVersionInfo](/boxlang-language/reference/built-in-functions/system/getboxversioninfo.md)
* [GetClassMetadata](/boxlang-language/reference/built-in-functions/system/getclassmetadata.md)
* [GetComponentList](/boxlang-language/reference/built-in-functions/system/getcomponentlist.md)
* [GetContextRoot](/boxlang-language/reference/built-in-functions/system/getcontextroot.md)
* [GetCurrentTemplatePath](/boxlang-language/reference/built-in-functions/system/getcurrenttemplatepath.md)
* [GetFileFromPath](/boxlang-language/reference/built-in-functions/system/getfilefrompath.md)
* [GetFunctionCalledName](/boxlang-language/reference/built-in-functions/system/getfunctioncalledname.md)
* [GetFunctionList](/boxlang-language/reference/built-in-functions/system/getfunctionlist.md)
* [GetModuleInfo](/boxlang-language/reference/built-in-functions/system/getmoduleinfo.md)
* [GetModuleList](/boxlang-language/reference/built-in-functions/system/getmodulelist.md)
* [GetModuleTree](/boxlang-language/reference/built-in-functions/system/getmoduletree.md)
* [GetRequestClassLoader](/boxlang-language/reference/built-in-functions/system/getrequestclassloader.md)
* [GetSemver](/boxlang-language/reference/built-in-functions/system/getsemver.md)
* [GetSystemSetting](/boxlang-language/reference/built-in-functions/system/getsystemsetting.md)
* [GetTempDirectory](/boxlang-language/reference/built-in-functions/system/gettempdirectory.md)
* [GetTickCount](/boxlang-language/reference/built-in-functions/system/gettickcount.md)
* [htmlEditFormat](/boxlang-language/reference/built-in-functions/system/htmleditformat.md)
* [IIF](/boxlang-language/reference/built-in-functions/system/iif.md)
* [Invoke](/boxlang-language/reference/built-in-functions/system/invoke.md)
* [IsInstanceOf](/boxlang-language/reference/built-in-functions/system/isinstanceof.md)
* [JavaCast](/boxlang-language/reference/built-in-functions/system/javacast.md)
* [ObjectDeserialize](/boxlang-language/reference/built-in-functions/system/objectdeserialize.md)
* [ObjectSerialize](/boxlang-language/reference/built-in-functions/system/objectserialize.md)
* [PagePoolClear](/boxlang-language/reference/built-in-functions/system/pagepoolclear.md)
* [Print](/boxlang-language/reference/built-in-functions/system/print.md)
* [Println](/boxlang-language/reference/built-in-functions/system/println.md)
* [RunThreadInContext](/boxlang-language/reference/built-in-functions/system/runthreadincontext.md)
* [SessionInvalidate](/boxlang-language/reference/built-in-functions/system/sessioninvalidate.md)
* [SessionRotate](/boxlang-language/reference/built-in-functions/system/sessionrotate.md)
* [SessionStartTime](/boxlang-language/reference/built-in-functions/system/sessionstarttime.md)
* [Sleep](/boxlang-language/reference/built-in-functions/system/sleep.md)
* [SystemCacheClear](/boxlang-language/reference/built-in-functions/system/systemcacheclear.md)
* [SystemExecute](/boxlang-language/reference/built-in-functions/system/systemexecute.md)
* [SystemOutput](/boxlang-language/reference/built-in-functions/system/systemoutput.md)
* [Trace](/boxlang-language/reference/built-in-functions/system/trace.md)
* [URLDecode](/boxlang-language/reference/built-in-functions/system/urldecode.md)
* [URLEncodedFormat](/boxlang-language/reference/built-in-functions/system/urlencodedformat.md)
* [writeDump](/boxlang-language/reference/built-in-functions/system/writedump.md)
* [WriteLog](/boxlang-language/reference/built-in-functions/system/writelog.md)
* [WriteOutput](/boxlang-language/reference/built-in-functions/system/writeoutput.md)


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