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@@ -5,7 +5,7 @@
**Table of contents**
- [Errors](#errors)
- [Error Handling In Node.js](#error-handling-in-node.js)
- [Error Handling In Node.js](#error-handling-in-nodejs)
- [Uncaught Errors](#uncaught-errors)
- [Catching Errors In Promises](#catching-errors-in-promises)
- [Errors In Fastify](#errors-in-fastify)
@@ -20,7 +20,6 @@
- [FST_ERR_SCHEMA_ERROR_FORMATTER_NOT_FN](#fst_err_schema_error_formatter_not_fn)
- [FST_ERR_AJV_CUSTOM_OPTIONS_OPT_NOT_OBJ](#fst_err_ajv_custom_options_opt_not_obj)
- [FST_ERR_AJV_CUSTOM_OPTIONS_OPT_NOT_ARR](#fst_err_ajv_custom_options_opt_not_arr)
- [FST_ERR_VERSION_CONSTRAINT_NOT_STR](#fst_err_version_constraint_not_str)
- [FST_ERR_CTP_ALREADY_PRESENT](#fst_err_ctp_already_present)
- [FST_ERR_CTP_INVALID_TYPE](#fst_err_ctp_invalid_type)
- [FST_ERR_CTP_EMPTY_TYPE](#fst_err_ctp_empty_type)
@@ -30,12 +29,15 @@
- [FST_ERR_CTP_INVALID_MEDIA_TYPE](#fst_err_ctp_invalid_media_type)
- [FST_ERR_CTP_INVALID_CONTENT_LENGTH](#fst_err_ctp_invalid_content_length)
- [FST_ERR_CTP_EMPTY_JSON_BODY](#fst_err_ctp_empty_json_body)
- [FST_ERR_CTP_INVALID_JSON_BODY](#fst_err_ctp_invalid_json_body)
- [FST_ERR_CTP_INSTANCE_ALREADY_STARTED](#fst_err_ctp_instance_already_started)
- [FST_ERR_INSTANCE_ALREADY_LISTENING](#fst_err_instance_already_listening)
- [FST_ERR_DEC_ALREADY_PRESENT](#fst_err_dec_already_present)
- [FST_ERR_DEC_DEPENDENCY_INVALID_TYPE](#fst_err_dec_dependency_invalid_type)
- [FST_ERR_DEC_MISSING_DEPENDENCY](#fst_err_dec_missing_dependency)
- [FST_ERR_DEC_AFTER_START](#fst_err_dec_after_start)
- [FST_ERR_DEC_REFERENCE_TYPE](#fst_err_dec_reference_type)
- [FST_ERR_DEC_UNDECLARED](#fst_err_dec_undeclared)
- [FST_ERR_HOOK_INVALID_TYPE](#fst_err_hook_invalid_type)
- [FST_ERR_HOOK_INVALID_HANDLER](#fst_err_hook_invalid_handler)
- [FST_ERR_HOOK_INVALID_ASYNC_HANDLER](#fst_err_hook_invalid_async_handler)
@@ -44,8 +46,12 @@
- [FST_ERR_HOOK_TIMEOUT](#fst_err_hook_timeout)
- [FST_ERR_LOG_INVALID_DESTINATION](#fst_err_log_invalid_destination)
- [FST_ERR_LOG_INVALID_LOGGER](#fst_err_log_invalid_logger)
- [FST_ERR_LOG_INVALID_LOGGER_INSTANCE](#fst_err_log_invalid_logger_instance)
- [FST_ERR_LOG_INVALID_LOGGER_CONFIG](#fst_err_log_invalid_logger_config)
- [FST_ERR_LOG_LOGGER_AND_LOGGER_INSTANCE_PROVIDED](#fst_err_log_logger_and_logger_instance_provided)
- [FST_ERR_REP_INVALID_PAYLOAD_TYPE](#fst_err_rep_invalid_payload_type)
- [FST_ERR_REP_RESPONSE_BODY_CONSUMED](#fst_err_rep_response_body_consumed)
- [FST_ERR_REP_READABLE_STREAM_LOCKED](#fst_err_rep_readable_stream_locked)
- [FST_ERR_REP_ALREADY_SENT](#fst_err_rep_already_sent)
- [FST_ERR_REP_SENT_VALUE](#fst_err_rep_sent_value)
- [FST_ERR_SEND_INSIDE_ONERR](#fst_err_send_inside_onerr)
@@ -64,13 +70,11 @@
- [FST_ERR_SCH_VALIDATION_BUILD](#fst_err_sch_validation_build)
- [FST_ERR_SCH_SERIALIZATION_BUILD](#fst_err_sch_serialization_build)
- [FST_ERR_SCH_RESPONSE_SCHEMA_NOT_NESTED_2XX](#fst_err_sch_response_schema_not_nested_2xx)
- [FST_ERR_HTTP2_INVALID_VERSION](#fst_err_http2_invalid_version)
- [FST_ERR_INIT_OPTS_INVALID](#fst_err_init_opts_invalid)
- [FST_ERR_FORCE_CLOSE_CONNECTIONS_IDLE_NOT_AVAILABLE](#fst_err_force_close_connections_idle_not_available)
- [FST_ERR_DUPLICATED_ROUTE](#fst_err_duplicated_route)
- [FST_ERR_BAD_URL](#fst_err_bad_url)
- [FST_ERR_ASYNC_CONSTRAINT](#fst_err_async_constraint)
- [FST_ERR_DEFAULT_ROUTE_INVALID_TYPE](#fst_err_default_route_invalid_type)
- [FST_ERR_INVALID_URL](#fst_err_invalid_url)
- [FST_ERR_ROUTE_OPTIONS_NOT_OBJ](#fst_err_route_options_not_obj)
- [FST_ERR_ROUTE_DUPLICATED_HANDLER](#fst_err_route_duplicated_handler)
@@ -90,16 +94,18 @@
- [FST_ERR_PARENT_PLUGIN_BOOTED](#fst_err_parent_plugin_booted)
- [FST_ERR_PLUGIN_TIMEOUT](#fst_err_plugin_timeout)
- [FST_ERR_PLUGIN_NOT_PRESENT_IN_INSTANCE](#fst_err_plugin_not_present_in_instance)
- [FST_ERR_PLUGIN_INVALID_ASYNC_HANDLER](#fst_err_plugin_invalid_async_handler)
- [FST_ERR_VALIDATION](#fst_err_validation)
- [FST_ERR_LISTEN_OPTIONS_INVALID](#fst_err_listen_options_invalid)
- [FST_ERR_ERROR_HANDLER_NOT_FN](#fst_err_error_handler_not_fn)
- [FST_ERR_ERROR_HANDLER_ALREADY_SET](#fst_err_error_handler_already_set)
### Error Handling In Node.js
<a id="error-handling"></a>
#### Uncaught Errors
In Node.js, uncaught errors are likely to cause memory leaks, file descriptor
leaks, and other major production issues.
In Node.js, uncaught errors can cause memory leaks, file descriptor leaks, and
other major production issues.
[Domains](https://nodejs.org/en/docs/guides/domain-postmortem/) were a failed
attempt to fix this.
@@ -108,29 +114,28 @@ way to deal with them is to
[crash](https://nodejs.org/api/process.html#process_warning_using_uncaughtexception_correctly).
#### Catching Errors In Promises
If you are using promises, you should attach a `.catch()` handler synchronously.
When using promises, attach a `.catch()` handler synchronously.
### Errors In Fastify
Fastify follows an all-or-nothing approach and aims to be lean and optimal as
much as possible. The developer is responsible for making sure that the errors
are handled properly.
Fastify follows an all-or-nothing approach and aims to be lean and optimal. The
developer is responsible for ensuring errors are handled properly.
#### Errors In Input Data
Most errors are a result of unexpected input data, so we recommend [validating
your input data against a JSON schema](./Validation-and-Serialization.md).
Most errors result from unexpected input data, so it is recommended to
[validate input data against a JSON schema](./Validation-and-Serialization.md).
#### Catching Uncaught Errors In Fastify
Fastify tries to catch as many uncaught errors as it can without hindering
Fastify tries to catch as many uncaught errors as possible without hindering
performance. This includes:
1. synchronous routes, e.g. `app.get('/', () => { throw new Error('kaboom') })`
2. `async` routes, e.g. `app.get('/', async () => { throw new Error('kaboom')
})`
The error in both cases will be caught safely and routed to Fastify's default
error handler for a generic `500 Internal Server Error` response.
In both cases, the error will be caught safely and routed to Fastify's default
error handler, resulting in a generic `500 Internal Server Error` response.
To customize this behavior you should use
To customize this behavior, use
[`setErrorHandler`](./Server.md#seterrorhandler).
### Errors In Fastify Lifecycle Hooks And A Custom Error Handler
@@ -140,52 +145,50 @@ From the [Hooks documentation](./Hooks.md#manage-errors-from-a-hook):
> `done()` and Fastify will automatically close the request and send the
> appropriate error code to the user.
When a custom error handler has been defined through
[`setErrorHandler`](./Server.md#seterrorhandler), the custom error handler will
receive the error passed to the `done()` callback (or through other supported
automatic error handling mechanisms). If `setErrorHandler` has been used
multiple times to define multiple handlers, the error will be routed to the most
precedent handler defined within the error [encapsulation
context](./Encapsulation.md). Error handlers are fully encapsulated, so a
`setErrorHandler` call within a plugin will limit the error handler to that
plugin's context.
When a custom error handler is defined through
[`setErrorHandler`](./Server.md#seterrorhandler), it will receive the error
passed to the `done()` callback or through other supported automatic error
handling mechanisms. If `setErrorHandler` is used multiple times, the error will
be routed to the most precedent handler within the error
[encapsulation context](./Encapsulation.md). Error handlers are fully
encapsulated, so a `setErrorHandler` call within a plugin will limit the error
handler to that plugin's context.
The root error handler is Fastify's generic error handler. This error handler
will use the headers and status code in the `Error` object, if they exist. The
headers and status code will not be automatically set if a custom error handler
is provided.
Some things to consider in your custom error handler:
The following should be considered when using a custom error handler:
- you can `reply.send(data)`, which will behave as it would in [regular route
handlers](./Reply.md#senddata)
- `reply.send(data)` behaves as in [regular route handlers](./Reply.md#senddata)
- objects are serialized, triggering the `preSerialization` lifecycle hook if
you have one defined
- strings, buffers, and streams are sent to the client, with appropriate
headers (no serialization)
defined
- strings, buffers, and streams are sent to the client with appropriate headers
(no serialization)
- You can throw a new error in your custom error handler - errors (new error or
the received error parameter re-thrown) - will call the parent `errorHandler`.
- `onError` hook will be triggered once only for the first error being thrown.
- an error will not be triggered twice from a lifecycle hook - Fastify
internally monitors the error invocation to avoid infinite loops for errors
thrown in the reply phases of the lifecycle. (those after the route handler)
- Throwing a new error in a custom error handler will call the parent
`errorHandler`.
- The `onError` hook will be triggered once for the first error thrown
- An error will not be triggered twice from a lifecycle hook. Fastify
internally monitors error invocation to avoid infinite loops for errors
thrown in the reply phases of the lifecycle (those after the route handler)
When utilizing Fastify's custom error handling through [`setErrorHandler`](./Server.md#seterrorhandler),
you should be aware of how errors are propagated between custom and default
error handlers.
When using Fastify's custom error handling through
[`setErrorHandler`](./Server.md#seterrorhandler), be aware of how errors are
propagated between custom and default error handlers.
If a plugin's error handler re-throws an error, and the error is not an
instance of [Error](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)
(as seen in the `/bad` route in the following example), it will not propagate
to the parent context error handler. Instead, it will be caught by the default
error handler.
If a plugin's error handler re-throws an error that is not an instance of
[Error](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error),
it will not propagate to the parent context error handler. Instead, it will be
caught by the default error handler. This can be seen in the `/bad` route of the
example below.
To ensure consistent error handling, it is recommended to throw instances of
`Error`. For instance, in the following example, replacing `throw 'foo'` with
`throw new Error('foo')` in the `/bad` route ensures that errors propagate through
the custom error handling chain as intended. This practice helps avoid potential
pitfalls when working with custom error handling in Fastify.
To ensure consistent error handling, throw instances of `Error`. For example,
replace `throw 'foo'` with `throw new Error('foo')` in the `/bad` route to
ensure errors propagate through the custom error handling chain as intended.
This practice helps avoid potential pitfalls when working with custom error
handling in Fastify.
For example:
```js
@@ -238,7 +241,7 @@ You can access `errorCodes` for mapping:
// ESM
import { errorCodes } from 'fastify'
// CommonJs
// CommonJS
const errorCodes = require('fastify').errorCodes
```
@@ -263,7 +266,7 @@ fastify.setErrorHandler(function (error, request, reply) {
// Send error response
reply.status(500).send({ ok: false })
} else {
// fastify will use parent error handler to handle this
// Fastify will use parent error handler to handle this
reply.send(error)
}
})
@@ -278,7 +281,7 @@ fastify.listen({ port: 3000 }, function (err, address) {
})
```
Below is a table with all the error codes that Fastify uses.
Below is a table with all the error codes used by Fastify.
| Code | Description | How to solve | Discussion |
|------|-------------|--------------|------------|
@@ -289,7 +292,6 @@ Below is a table with all the error codes that Fastify uses.
| <a id="fst_err_schema_error_formatter_not_fn">FST_ERR_SCHEMA_ERROR_FORMATTER_NOT_FN</a> | SchemaErrorFormatter option wrongly specified. | SchemaErrorFormatter option should be a non async function. | [#4554](https://github.com/fastify/fastify/pull/4554) |
| <a id="fst_err_ajv_custom_options_opt_not_obj">FST_ERR_AJV_CUSTOM_OPTIONS_OPT_NOT_OBJ</a> | ajv.customOptions wrongly specified. | ajv.customOptions option should be an object. | [#4554](https://github.com/fastify/fastify/pull/4554) |
| <a id="fst_err_ajv_custom_options_opt_not_arr">FST_ERR_AJV_CUSTOM_OPTIONS_OPT_NOT_ARR</a> | ajv.plugins option wrongly specified. | ajv.plugins option should be an array. | [#4554](https://github.com/fastify/fastify/pull/4554) |
| <a id="fst_err_version_constraint_not_str">FST_ERR_VERSION_CONSTRAINT_NOT_STR</a> | Version constraint wrongly specified. | Version constraint should be a string. | [#4554](https://github.com/fastify/fastify/pull/4554) |
| <a id="fst_err_ctp_already_present">FST_ERR_CTP_ALREADY_PRESENT</a> | The parser for this content type was already registered. | Use a different content type or delete the already registered parser. | [#1168](https://github.com/fastify/fastify/pull/1168) |
| <a id="fst_err_ctp_invalid_type">FST_ERR_CTP_INVALID_TYPE</a> | `Content-Type` wrongly specified | The `Content-Type` should be a string. | [#1168](https://github.com/fastify/fastify/pull/1168) |
| <a id="fst_err_ctp_empty_type">FST_ERR_CTP_EMPTY_TYPE</a> | `Content-Type` is an empty string. | `Content-Type` cannot be an empty string. | [#1168](https://github.com/fastify/fastify/pull/1168) |
@@ -298,13 +300,16 @@ Below is a table with all the error codes that Fastify uses.
| <a id="fst_err_ctp_body_too_large">FST_ERR_CTP_BODY_TOO_LARGE</a> | The request body is larger than the provided limit. | Increase the limit in the Fastify server instance setting: [bodyLimit](./Server.md#bodylimit) | [#1168](https://github.com/fastify/fastify/pull/1168) |
| <a id="fst_err_ctp_invalid_media_type">FST_ERR_CTP_INVALID_MEDIA_TYPE</a> | The received media type is not supported (i.e. there is no suitable `Content-Type` parser for it). | Use a different content type. | [#1168](https://github.com/fastify/fastify/pull/1168) |
| <a id="fst_err_ctp_invalid_content_length">FST_ERR_CTP_INVALID_CONTENT_LENGTH</a> | Request body size did not match <code>Content-Length</code>. | Check the request body size and the <code>Content-Length</code> header. | [#1168](https://github.com/fastify/fastify/pull/1168) |
| <a id="fst_err_ctp_empty_json_body">FST_ERR_CTP_EMPTY_JSON_BODY</a> | Body cannot be empty when content-type is set to <code>application/json</code>. | Check the request body. | [#1253](https://github.com/fastify/fastify/pull/1253) |
| <a id="fst_err_ctp_empty_json_body">FST_ERR_CTP_EMPTY_JSON_BODY</a> | Body is not valid JSON but content-type is set to <code>application/json</code>. | Check if the request body is valid JSON. | [#5925](https://github.com/fastify/fastify/pull/5925) |
| <a id="fst_err_ctp_invalid_json_body">FST_ERR_CTP_INVALID_JSON_BODY</a> | Body cannot be empty when content-type is set to <code>application/json</code>. | Check the request body. | [#1253](https://github.com/fastify/fastify/pull/1253) |
| <a id="fst_err_ctp_instance_already_started">FST_ERR_CTP_INSTANCE_ALREADY_STARTED</a> | Fastify is already started. | - | [#4554](https://github.com/fastify/fastify/pull/4554) |
| <a id="fst_err_instance_already_listening">FST_ERR_INSTANCE_ALREADY_LISTENING</a> | Fastify instance is already listening. | - | [#4554](https://github.com/fastify/fastify/pull/4554) |
| <a id="fst_err_dec_already_present">FST_ERR_DEC_ALREADY_PRESENT</a> | A decorator with the same name is already registered. | Use a different decorator name. | [#1168](https://github.com/fastify/fastify/pull/1168) |
| <a id="fst_err_dec_dependency_invalid_type">FST_ERR_DEC_DEPENDENCY_INVALID_TYPE</a> | The dependencies of decorator must be of type `Array`. | Use an array for the dependencies. | [#3090](https://github.com/fastify/fastify/pull/3090) |
| <a id="fst_err_dec_missing_dependency">FST_ERR_DEC_MISSING_DEPENDENCY</a> | The decorator cannot be registered due to a missing dependency. | Register the missing dependency. | [#1168](https://github.com/fastify/fastify/pull/1168) |
| <a id="fst_err_dec_after_start">FST_ERR_DEC_AFTER_START</a> | The decorator cannot be added after start. | Add the decorator before starting the server. | [#2128](https://github.com/fastify/fastify/pull/2128) |
| <a id="fst_err_dec_reference_type">FST_ERR_DEC_REFERENCE_TYPE</a> | The decorator cannot be a reference type. | Define the decorator with a getter/setter interface or an empty decorator with a hook. | [#5462](https://github.com/fastify/fastify/pull/5462) |
| <a id="fst_err_dec_undeclared">FST_ERR_DEC_UNDECLARED</a> | An attempt was made to access a decorator that has not been declared. | Declare the decorator before using it. | [#](https://github.com/fastify/fastify/pull/)
| <a id="fst_err_hook_invalid_type">FST_ERR_HOOK_INVALID_TYPE</a> | The hook name must be a string. | Use a string for the hook name. | [#1168](https://github.com/fastify/fastify/pull/1168) |
| <a id="fst_err_hook_invalid_handler">FST_ERR_HOOK_INVALID_HANDLER</a> | The hook callback must be a function. | Use a function for the hook callback. | [#1168](https://github.com/fastify/fastify/pull/1168) |
| <a id="fst_err_hook_invalid_async_handler">FST_ERR_HOOK_INVALID_ASYNC_HANDLER</a> | Async function has too many arguments. Async hooks should not use the `done` argument. | Remove the `done` argument from the async hook. | [#4367](https://github.com/fastify/fastify/pull/4367) |
@@ -313,8 +318,12 @@ Below is a table with all the error codes that Fastify uses.
| <a id="fst_err_hook_timeout">FST_ERR_HOOK_TIMEOUT</a> | A callback for a hook timed out. | Increase the timeout for the hook. | [#3106](https://github.com/fastify/fastify/pull/3106) |
| <a id="fst_err_log_invalid_destination">FST_ERR_LOG_INVALID_DESTINATION</a> | The logger does not accept the specified destination. | Use a `'stream'` or a `'file'` as the destination. | [#1168](https://github.com/fastify/fastify/pull/1168) |
| <a id="fst_err_log_invalid_logger">FST_ERR_LOG_INVALID_LOGGER</a> | The logger should have all these methods: `'info'`, `'error'`, `'debug'`, `'fatal'`, `'warn'`, `'trace'`, `'child'`. | Use a logger with all the required methods. | [#4520](https://github.com/fastify/fastify/pull/4520) |
| <a id="fst_err_log_invalid_logger_instance">FST_ERR_LOG_INVALID_LOGGER_INSTANCE</a> | The `loggerInstance` only accepts a logger instance, not a configuration object. | To pass a configuration object, use `'logger'` instead. | [#5020](https://github.com/fastify/fastify/pull/5020) |
| <a id="fst_err_log_invalid_logger_config">FST_ERR_LOG_INVALID_LOGGER_CONFIG</a> | The logger option only accepts a configuration object, not a logger instance. | To pass an instance, use `'loggerInstance'` instead. | [#5020](https://github.com/fastify/fastify/pull/5020) |
| <a id="fst_err_log_logger_and_logger_instance_provided">FST_ERR_LOG_LOGGER_AND_LOGGER_INSTANCE_PROVIDED</a> | You cannot provide both `'logger'` and `'loggerInstance'`. | Please provide only one option. | [#5020](https://github.com/fastify/fastify/pull/5020) |
| <a id="fst_err_rep_invalid_payload_type">FST_ERR_REP_INVALID_PAYLOAD_TYPE</a> | Reply payload can be either a `string` or a `Buffer`. | Use a `string` or a `Buffer` for the payload. | [#1168](https://github.com/fastify/fastify/pull/1168) |
| <a id="fst_err_rep_response_body_consumed">FST_ERR_REP_RESPONSE_BODY_CONSUMED</a> | Using `Response` as reply payload, but the body is being consumed. | Make sure you don't consume the `Response.body` | [#5286](https://github.com/fastify/fastify/pull/5286) |
| <a id="fst_err_rep_readable_stream_locked">FST_ERR_REP_READABLE_STREAM_LOCKED</a> | Using `ReadableStream` as reply payload, but locked with another reader. | Make sure you don't call the `Readable.getReader` before sending or release lock with `reader.releaseLock()` before sending. | [#5920](https://github.com/fastify/fastify/pull/5920) |
| <a id="fst_err_rep_already_sent">FST_ERR_REP_ALREADY_SENT</a> | A response was already sent. | - | [#1336](https://github.com/fastify/fastify/pull/1336) |
| <a id="fst_err_rep_sent_value">FST_ERR_REP_SENT_VALUE</a> | The only possible value for `reply.sent` is `true`. | - | [#1336](https://github.com/fastify/fastify/pull/1336) |
| <a id="fst_err_send_inside_onerr">FST_ERR_SEND_INSIDE_ONERR</a> | You cannot use `send` inside the `onError` hook. | - | [#1348](https://github.com/fastify/fastify/pull/1348) |
@@ -333,13 +342,11 @@ Below is a table with all the error codes that Fastify uses.
| <a id="fst_err_sch_validation_build">FST_ERR_SCH_VALIDATION_BUILD</a> | The JSON schema provided for validation to a route is not valid. | Fix the JSON schema. | [#2023](https://github.com/fastify/fastify/pull/2023) |
| <a id="fst_err_sch_serialization_build">FST_ERR_SCH_SERIALIZATION_BUILD</a> | The JSON schema provided for serialization of a route response is not valid. | Fix the JSON schema. | [#2023](https://github.com/fastify/fastify/pull/2023) |
| <a id="fst_err_sch_response_schema_not_nested_2xx">FST_ERR_SCH_RESPONSE_SCHEMA_NOT_NESTED_2XX</a> | Response schemas should be nested under a valid status code (2XX). | Use a valid status code. | [#4554](https://github.com/fastify/fastify/pull/4554) |
| <a id="fst_err_http2_invalid_version">FST_ERR_HTTP2_INVALID_VERSION</a> | HTTP2 is available only from node >= 8.8.1. | Use a higher version of node. | [#1346](https://github.com/fastify/fastify/pull/1346) |
| <a id="fst_err_init_opts_invalid">FST_ERR_INIT_OPTS_INVALID</a> | Invalid initialization options. | Use valid initialization options. | [#1471](https://github.com/fastify/fastify/pull/1471) |
| <a id="fst_err_force_close_connections_idle_not_available">FST_ERR_FORCE_CLOSE_CONNECTIONS_IDLE_NOT_AVAILABLE</a> | Cannot set forceCloseConnections to `idle` as your HTTP server does not support `closeIdleConnections` method. | Use a different value for `forceCloseConnections`. | [#3925](https://github.com/fastify/fastify/pull/3925) |
| <a id="fst_err_duplicated_route">FST_ERR_DUPLICATED_ROUTE</a> | The HTTP method already has a registered controller for that URL. | Use a different URL or register the controller for another HTTP method. | [#2954](https://github.com/fastify/fastify/pull/2954) |
| <a id="fst_err_bad_url">FST_ERR_BAD_URL</a> | The router received an invalid URL. | Use a valid URL. | [#2106](https://github.com/fastify/fastify/pull/2106) |
| <a id="fst_err_async_constraint">FST_ERR_ASYNC_CONSTRAINT</a> | The router received an error when using asynchronous constraints. | - | [#4323](https://github.com/fastify/fastify/pull/4323) |
| <a id="fst_err_default_route_invalid_type">FST_ERR_DEFAULT_ROUTE_INVALID_TYPE</a> | The `defaultRoute` type should be a function. | Use a function for the `defaultRoute`. | [#2733](https://github.com/fastify/fastify/pull/2733) |
| <a id="fst_err_invalid_url">FST_ERR_INVALID_URL</a> | URL must be a string. | Use a string for the URL. | [#3653](https://github.com/fastify/fastify/pull/3653) |
| <a id="fst_err_route_options_not_obj">FST_ERR_ROUTE_OPTIONS_NOT_OBJ</a> | Options for the route must be an object. | Use an object for the route options. | [#4554](https://github.com/fastify/fastify/pull/4554) |
| <a id="fst_err_route_duplicated_handler">FST_ERR_ROUTE_DUPLICATED_HANDLER</a> | Duplicate handler for the route is not allowed. | Use a different handler. | [#4554](https://github.com/fastify/fastify/pull/4554) |
@@ -359,7 +366,7 @@ Below is a table with all the error codes that Fastify uses.
| <a id="fst_err_parent_plugin_booted">FST_ERR_PARENT_PLUGIN_BOOTED</a> | Impossible to load plugin because the parent (mapped directly from `avvio`) | - | [#3106](https://github.com/fastify/fastify/pull/3106) |
| <a id="fst_err_plugin_timeout">FST_ERR_PLUGIN_TIMEOUT</a> | Plugin did not start in time. | Increase the timeout for the plugin. | [#3106](https://github.com/fastify/fastify/pull/3106) |
| <a id="fst_err_plugin_not_present_in_instance">FST_ERR_PLUGIN_NOT_PRESENT_IN_INSTANCE</a> | The decorator is not present in the instance. | - | [#4554](https://github.com/fastify/fastify/pull/4554) |
| <a id="fst_err_plugin_invalid_async_handler">FST_ERR_PLUGIN_INVALID_ASYNC_HANDLER</a> | The plugin being registered mixes async and callback styles. | - | [#5141](https://github.com/fastify/fastify/pull/5141) |
| <a id="fst_err_validation">FST_ERR_VALIDATION</a> | The Request failed the payload validation. | Check the request payload. | [#4824](https://github.com/fastify/fastify/pull/4824) |
| <a id="fst_err_listen_options_invalid">FST_ERR_LISTEN_OPTIONS_INVALID</a> | Invalid listen options. | Check the listen options. | [#4886](https://github.com/fastify/fastify/pull/4886) |
| <a id="fst_err_error_handler_not_fn">FST_ERR_ERROR_HANDLER_NOT_FN</a> | Error Handler must be a function | Provide a function to `setErrorHandler`. | [#5317](https://github.com/fastify/fastify/pull/5317) |
| <a id="fst_err_error_handler_not_fn">FST_ERR_ERROR_HANDLER_NOT_FN</a> | Error Handler must be a function | Provide a function to `setErrorHandler`. | [#5317](https://github.com/fastify/fastify/pull/5317) | <a id="fst_err_error_handler_already_set">FST_ERR_ERROR_HANDLER_ALREADY_SET</a> | Error Handler already set in this scope. Set `allowErrorHandlerOverride: true` to allow overriding. | By default, `setErrorHandler` can only be called once per encapsulation context. | [#6097](https://github.com/fastify/fastify/pull/6098) |