diff --git a/src/content/docs/en/reference/error-reference.mdx b/src/content/docs/en/reference/error-reference.mdx
index f0aab46987572..d3aa641eb7585 100644
--- a/src/content/docs/en/reference/error-reference.mdx
+++ b/src/content/docs/en/reference/error-reference.mdx
@@ -128,5 +128,6 @@ The following reference is a complete list of the errors you may encounter while
 
 - [**ActionsWithoutServerOutputError**](/en/reference/errors/actions-without-server-output-error/)<br/>Actions must be used with server output.
 - [**ActionsUsedWithForGetError**](/en/reference/errors/actions-used-with-for-get-error/)<br/>An invalid Action query string was passed by a form.
+- [**ActionsReturnedInvalidDataError**](/en/reference/errors/actions-returned-invalid-data-error/)<br/>Action handler returned invalid data.
 - [**ActionQueryStringInvalidError**](/en/reference/errors/action-query-string-invalid-error/)<br/>An invalid Action query string was passed by a form.
 - [**ActionCalledFromServerError**](/en/reference/errors/action-called-from-server-error/)<br/>Action unexpected called from the server.
diff --git a/src/content/docs/en/reference/errors/actions-returned-invalid-data-error.mdx b/src/content/docs/en/reference/errors/actions-returned-invalid-data-error.mdx
new file mode 100644
index 0000000000000..f763a2fcf0dd1
--- /dev/null
+++ b/src/content/docs/en/reference/errors/actions-returned-invalid-data-error.mdx
@@ -0,0 +1,24 @@
+---
+# NOTE: This file is auto-generated from 'scripts/error-docgen.mjs'
+# Do not make edits to it directly, they will be overwritten.
+# Instead, change this file: https://github.com/withastro/astro/blob/main/packages/astro/src/core/errors/errors-data.ts
+# Translators, please remove this note and the <DontEditWarning/> component.
+
+title: Action handler returned invalid data.
+i18nReady: true
+githubURL: https://github.com/withastro/astro/blob/main/packages/astro/src/core/errors/errors-data.ts
+---
+import DontEditWarning from '~/components/DontEditWarning.astro'
+
+<DontEditWarning />
+
+
+> **ActionsReturnedInvalidDataError**: Action handler returned invalid data. Handlers should return serializable data types like objects, arrays, strings, and numbers. Parse error: ERROR
+
+## What went wrong?
+Action handler returned invalid data. Handlers should return serializable data types, and cannot return a Response object.
+
+**See Also:**
+-  [Actions RFC](https://github.com/withastro/roadmap/blob/actions/proposals/0046-actions.md)
+
+