Maximum Number of Domains Allowed in Home Realm Discovery for SAML Connections

Knowledge Articles
1

Overview

When configuring a SAML connection in Auth0, the Home Realm Discovery section allows administrators to specify identity provider (IdP) domains for automatic redirection. Some users may need to add a large number of domains, raising the question of whether there is a limit. This article will explain the limits and strategies for dealing with situations that require more than that limit.

Applies To

  • SAML Enterprise Connections in Auth0
  • Home Realm Discovery (options.domain_aliases)
  • Large-scale IdP domain management

Solution

Auth0 enforces a 1,000-domain limit on the options.domain_aliases property for SAML connections. If more than 1,000 domains are added, an API request will fail with the following error:

{

  "statusCode": 400,

  "error": "Bad Request",

  "message": "'Array is too long (1036), maximum 1000' on property options.domain_aliases",

  "errorCode": "invalid_body"

}

This ensures system stability and prevents performance issues associated with excessive domain lookups.

If more than 1,000 domains are required, consider the following options:

  1. Consolidate Domains:
    • If possible, group similar domains under a smaller number of shared domains to stay within the limit.
  2. Contact Auth0 Professional Services:
    • If the use case requires an exception or alternative implementation, contact Auth0 Professional Services to explore potential solutions.