Form Handler Submissions from an External Site Fails with a Browser Security Error

Publish Date: Jul 7, 2026

Description

When submitting to a Form Handler endpoint from an external site, you may encounter that:

The submission fails and no data is captured.
Browser developer tools (Network tab) show a failed request with a security error (may mention "cross-origin" or "blocked").

Resolution

This configuration can only be applied by Salesforce Support. Contact Salesforce Support and reference this article.

Knowledge Article Number

005388607

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