---
title: MARKLESS_CHILDREN_OPAQUE
description: "Code maps, counts, indexes, or changes children."
sidebar: { hidden: true }
search: { keywords: ["CHILDREN_OPAQUE","children opaque","markless error"] }
pagination: false
---

**Error** from the compiler, while it builds your `.tsrx` files.

## What happened

You can place `{children}`, wrap it, or pass it on. You cannot map, count, index, or change it.

Markless prints the message, the reason, and a suggestion:

```text
MARKLESS_CHILDREN_OPAQUE: children is an opaque template projection: place it with {children}, wrap it, or pass it through — mapping, counting, indexing, or mutating it is not supported.
The compiler owns children projection; there is no render-output array to inspect, so React-style children access would silently misbehave.
Render {children} directly or move per-item rendering to the parent.
https://markless.dev/errors/MARKLESS_CHILDREN_OPAQUE
```

## How to fix it

Render `{children}` as it is. If you need markup per item, render the items in the parent.

## Where it comes from

`@markless/compiler` raises this code. Source:

- [packages/compiler/src/passes/public-render/diagnostics.ts](https://github.com/compiled-run/markless/blob/main/packages/compiler/src/passes/public-render/diagnostics.ts)

Read [how to read a Markless error](/tooling/diagnostics), or go back to [all error codes](/errors).