Updating a Cognito Login Error Message

Question

We are using the Hosted UI for a Cognito User Pool and the following issue has been identified:
 
When users are on the hosted login page (e.g. myuserpool.auth.region.amazoncognito.com/login) and the "client_id" query parameter is modified so that it references an invalid or nonexisting App Client ID, the page redirects to a hosted error page (e.g. myuserpool.auth.region.amazoncognito.com/error) where the URL contains a query parameter "error" whose value is "Client does not exist".
 
Is there any way to modify the behavior of this redirect such that the "error" query parameter's value contains a more generic message like "An error occured," similar to the error message that is shown in the UI ("An error was encountered with the requested page.")?

Answer

Hello,

It is not possible to customize error messages currently. but revealing that a client exists or not doesn't have risks in my opinion, these IDs are random strings created by Cognito and considered public information (like a domain name, not a secret).

Updating a Cognito Login Error Message

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