> ## Documentation Index
> Fetch the complete documentation index at: https://docs.argyle.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Error Codes
Link errors: common causes and troubleshooting.
## Overview
When a user encounters an error in Link, they are shown an error screen that displays suggestions for resolving the particular issue. *For easier troubleshooting, we recommend you include the* `onError` *[callback](/link/reference/callbacks#onerror) in your Link initialization.*
The `onError` callback returns:
```json theme={}
LinkError (
"userId": String, // ID of the user
"errorType": String (enum), // Error name
"errorMessage": String, // User message
"errorDetails": String // Error details
)
```
## Link errors
### `callback_undefined`
This page does not exist. Reach out to \[Company name] for help.
Reason: callback undefined (`onCantFindItemClicked`)
The **Callback** experience type was selected for **"If no results"** when customizing a Link Flow, but the `onCantFindItemClicked` callback was not included in the Link initialization.
Include the `onCantFindItemClicked` callback in your Link initialization.
### `duplicate_account`
This User ID is already associated with a connected account. Please try a different User ID to connect another account.
none
The user attempted to connect an already-connected account.
Advise the user to double-check which log in credentials they currently or originally used for the intended employer.
### `expired_user_token`
The service is experiencing connection problems. Please try again later.
User ID: `` (see [user ID](/api-reference/users))
Reason: expired `userToken`
Link was initialized with an expired user token, or the user token expired during the Link session.
Create a new user token, and either:
1. Re-initialize Link with the new user token.
2. Pass the new user token to the `onTokenExpired` [callback](/link/reference/callbacks#ontokenexpired) to continue the existing Link session.
### `generic`
The service is experiencing connection problems. Please try again later.
none
An unexpected error occurred. We are looking into it.
Contact our support team for more details.
### `invalid_account_id`
The page does not exist. Reach out the \[Company] for help.
Reason: invalid accountId
An invalid `accountId` was used for [direct login to an existing account](/workflows/account-connections#existing-connections) when initializing Link.
Use the [accounts API endpoint](/api-reference/accounts#list) with the user's `id` as a query parameter to see a list of valid `accountId`'s for the user.
### `invalid_items`
This page does not exist. Reach out to \[Company name] for help.
Reason: invalid custom items
* [Direct login](/workflows/account-connections#direct-login) was used for an Item that does not exist.
* Link search was constrained to Items that do not exist.
* Link was initialized with the optional `items` [initialization parameter](/link/initialization/overview#optional-initialization-parameters) but an empty array was present.
Use the Items endpoint and Console's Coverage page to check Item availability.
### `invalid_user_token`
The service is experiencing connection problems. Please try again later.
Reason: invalid userToken
The [user token](/link/user-tokens) provided in the Link initialization was not valid.
Check the user token was provided correctly in the Link initialization. See our [user tokens guide](/link/user-tokens) for more information.
