---
title: MARKLESS_SERIALIZE_UNSUPPORTED_VALUE
description: "State holds a value that Markless cannot send from the server to the browser."
sidebar: { hidden: true }
search: { keywords: ["SERIALIZE_UNSUPPORTED_VALUE","serialize unsupported value","markless error"] }
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---

**Error** from the runtime, while a page renders or runs.

## What happened

Markless sends state from the server to the browser as data. This value is a function or a live object, so it cannot travel that way.

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

```text
MARKLESS_SERIALIZE_UNSUPPORTED_VALUE: Cannot serialize value at <cellPrefix> because unknown values are not durable graph state.
Serialization is for durable graph state. Functions and host/runtime resources cannot be restored during resume.
Move runtime resources into attach={...}, make the value serializable state, or derive it with computed().
https://markless.dev/errors/MARKLESS_SERIALIZE_UNSUPPORTED_VALUE
```

Words in angle brackets change from case to case.

## How to fix it

Keep plain data in state. Create live objects, like sockets, in an `attach={...}` behavior on an element. If the value comes from other state, use `computed()`.

## Where it comes from

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

- [packages/serializer/src/protocol-state.ts](https://github.com/compiled-run/markless/blob/main/packages/serializer/src/protocol-state.ts)
- [packages/serializer/src/value.ts](https://github.com/compiled-run/markless/blob/main/packages/serializer/src/value.ts)
- [packages/web/src/fns/state-slot.ts](https://github.com/compiled-run/markless/blob/main/packages/web/src/fns/state-slot.ts)

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