3.6.8. Throwing and Handling Errors

In this guide, you'll learn how to throw errors in your Medusa application, how it affects an API route's response, and how to change the default error handler of your Medusa application.

Throw MedusaError#

When throwing an error in your API routes, middlewares, workflows, or any customization, throw a MedusaError from the Medusa Framework.

The Medusa application's API route error handler then wraps your thrown error in a uniform object and returns it in the response.

For example:

Code
1import { MedusaRequest, MedusaResponse } from "@medusajs/framework/http"2import { MedusaError } from "@medusajs/framework/utils"3
4export const GET = async (5  req: MedusaRequest,6  res: MedusaResponse7) => {8  if (!req.query.q) {9    throw new MedusaError(10      MedusaError.Types.INVALID_DATA,11      "The `q` query parameter is required."12    )13  }14
15  // ...16}

The MedusaError class accepts two parameters in its constructor:

1. The first is the error's type. MedusaError has a static property Types that you can use. Types is an enum whose possible values are explained in the next section.
2. The second is the message to show in the error response.

Error Object in Response#

The error object returned in the response has three properties:

• type: The error's type.
• message: The error message, if available.
• code: A common snake-case code. Its values can be:
  • invalid_request_error for the DUPLICATE_ERROR type.
  • api_error for the DB_ERROR type.
  • invalid_state_error for the CONFLICT error type.
  • unknown_error for any unidentified error type.
  • For other error types, this property won't be available unless you provide a code as a third parameter to the MedusaError constructor.

MedusaError Types#

Override Error Handler#

The defineMiddlewares function used to apply middlewares on routes accepts an errorHandler in its object parameter. Use it to override the default error handler for API routes.

For example, create src/api/middlewares.ts with the following:

src/api/middlewares.ts
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7import { MedusaError } from "@medusajs/framework/utils"8
9export default defineMiddlewares({10  errorHandler: (11    error: MedusaError | any, 12    req: MedusaRequest, 13    res: MedusaResponse, 14    next: MedusaNextFunction15  ) => {16    res.status(400).json({17      error: "Something happened.",18    })19  },20})

The errorHandler property's value is a function that accepts four parameters:

1. The error thrown. Its type can be MedusaError or any other error type.
2. A request object of type MedusaRequest.
3. A response object of type MedusaResponse.
4. A function of type MedusaNextFunction that executes the next middleware in the stack.

This example overrides Medusa's default error handler with a handler that always returns a 400 status code with the same message.

Re-Use Default Error Handler#

In some use cases, you may not want to override the default error handler but rather perform additional actions as part of the original error handler. For example, you might want to capture the error in a third-party service like Sentry.

In those cases, you can import the default error handler from the Medusa Framework and use it in your custom error handler, along with your custom logic.

For example:

src/api/middlewares.ts
1import { 2  defineMiddlewares, 3  errorHandler, 4  MedusaNextFunction, 5  MedusaRequest, 6  MedusaResponse,7} from "@medusajs/framework/http"8import { MedusaError } from "@medusajs/framework/utils"9// assuming you have Sentry set up in your project10import * as Sentry from "@sentry/node"11
12const originalErrorHandler = errorHandler()13
14export default defineMiddlewares({15  errorHandler: (16    error: MedusaError | any, 17    req: MedusaRequest, 18    res: MedusaResponse, 19    next: MedusaNextFunction20  ) => {21    // for example, capture the error in Sentry22    Sentry.captureException(error)23    return originalErrorHandler(error, req, res, next)24  },25})

In this example, you import the errorHandler function from the Medusa Framework. Then, you call it to get the original error handler function.

Finally, you use it in your custom error handler after performing your custom logic, such as capturing the error in Sentry.