---
title: MARKLESS_EVENT_HANDLER_EMIT_UNSUPPORTED
description: "An event handler reads a local variable that does not exist in the browser."
sidebar: { hidden: true }
search: { keywords: ["EVENT_HANDLER_EMIT_UNSUPPORTED","event handler emit unsupported","markless error"] }
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---

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

## What happened

The handler reads a plain local from the component body. The browser does not run the component body again, so that local does not exist when the click happens.

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

```text
MARKLESS_EVENT_HANDLER_EMIT_UNSUPPORTED: Cannot emit lazy <kind> symbol "<symbolId>" because it reads component-local "<name>", a local <bindingKindLabel> value that cannot cross a resume boundary.
Lazy handler symbols run after browser resume. Handler bodies may use graph references, element handles, props/shared values, module imports, or serializable capture-plane inputs; unsupported body locals would otherwise become silent no-op code.
https://markless.dev/errors/MARKLESS_EVENT_HANDLER_EMIT_UNSUPPORTED
```

Words in angle brackets change from case to case.

## How to fix it

Make the local `state()`. Or move it to the top of the file. Or build it only from props, state, and imports.

## Where it comes from

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

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

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