diff --git a/changelog.d/9933-util-inspect-lazy-error-stack.md b/changelog.d/9933-util-inspect-lazy-error-stack.md
new file mode 100644
index 0000000000..71a4dbb821
--- /dev/null
+++ b/changelog.d/9933-util-inspect-lazy-error-stack.md
@@ -0,0 +1,5 @@
+### Fixed
+
+- Materialize lazy Error stacks when `util.inspect()` formats an Error with a
+  `cause` or an `AggregateError` with `errors`, preserving Node-compatible
+  stack/body layout.
diff --git a/crates/perry-runtime/src/builtins/formatting/errors.rs b/crates/perry-runtime/src/builtins/formatting/errors.rs
index 76eaa7543c..d940f895d9 100644
--- a/crates/perry-runtime/src/builtins/formatting/errors.rs
+++ b/crates/perry-runtime/src/builtins/formatting/errors.rs
@@ -49,7 +49,13 @@ unsafe fn format_error_headline(error_ptr: *const crate::error::ErrorHeader) ->
 }
 
 unsafe fn format_error_stack_frame(error_ptr: *const crate::error::ErrorHeader) -> Option<String> {
-    let stack = string_header_to_string((*error_ptr).stack, "");
+    // #9486 made Error stacks lazy: `ErrorHeader.stack` stays null until the
+    // first observable read materializes the captured frame payload. Inspect
+    // is one of those reads. Looking at the slot directly made Errors with a
+    // cause or AggregateError.errors print a standalone `{` where Node keeps
+    // it attached to the final stack line.
+    let stack_ptr = crate::error::materialize_error_stack(error_ptr.cast_mut());
+    let stack = string_header_to_string(stack_ptr, "");
     stack
         .lines()
         .skip(1)