This is possible. The Index page can be customized through your FusionAuth theme. You can add a redirect (for example, using JavaScript or a meta refresh tag) to send users to your application's login page.

Important: When FusionAuth can't identify the tenant (including when browsing to / without client_id or tenantId parameters), it uses the default tenant. To theme the root page:

See the Advanced Themes troubleshooting guide for more details on theme issues.

Related: GitHub Issue #378

This is also possible. The OAuth error page can be customized in your theme, so you can implement the same redirect approach for customers who saved stale or broken login links. The OAuth error template is available for customization and you can add JavaScript or meta refresh redirects to handle these scenarios.

Note that OAuth errors can also be returned as redirect parameters to your application's callback URL (depending on the OAuth flow), which allows your application to handle errors directly rather than showing the FusionAuth-hosted error page.

This is NOT currently customizable. The 404 page cannot be customized, including on Cloud deployments. Requests to invalid paths (like /whatever) will show the default error page. This is a known limitation tracked in GitHub Issue #404, which requests additional themed error pages (including 404 and 500 pages).

You can handle root path and OAuth error redirects through theme customization by adding JavaScript redirects to the index and OAuth error templates. However, true 404 pages remain uncustomizable. CloudFront configuration is not exposed to customers on cloud deployments, so there's no workaround at that layer.

To fix this, you need to provide a safe fallback for the postMethod variable. Update line 16 in your registration/verify.ftl template from:

To:

The !false syntax provides a default value of false when postMethod is null or missing, preventing the FreeMarker exception.

Steps to apply the fix:

This pattern can be applied to other templates where variables might be null or missing in certain execution paths.

Why this happens:

According to the FusionAuth documentation, the postMethod variable is not a standard template-specific variable for the /registration/verify template. It is typically available on other verification templates like /email/verify (where it defaults to true). The registration verify template is rendered when a user clicks the URL from the verification email and the verificationId has expired or is invalid. In these scenarios, postMethod may not be set in the template context, which causes the FreeMarker error when attempting to evaluate it as a boolean.