> ## Documentation Index
> Fetch the complete documentation index at: https://docs.cowboy.inc/llms.txt
> Use this file to discover all available pages before exploring further.

# E1503 — Unauthorized timer mutation

> Unauthorized timer mutation

# E1503 — Unauthorized timer mutation

| Property | Value |
| - | - |
| **Code** | `1503` |
| **Slug** | `E1503` |
| **Category** | `timer` (Timer) |

## What happened

Unauthorized timer mutation: actor \{caller} cannot cancel or extend timer owned by \{owner}.

This is the receipt's `what` text, produced by the node's `ExecutionError::UnauthorizedTimerCancel`. Placeholders in braces are filled from the failing transaction.

## Why it happened

The node rejected the operation with `E1503` (category `timer`, Timer). The receipt's `why` field carries the specific cause and `context` carries structured details, such as the values that filled the placeholders above.

## How to fix

Only the actor that scheduled a timer may cancel or extend it. Use the timer\_id you obtained from schedule\_timer.

## Receipt example

```json theme={null}
{
  "code": 1503,
  "slug": "E1503",
  "category": "timer",
  "what": "unauthorized timer mutation: actor {caller} cannot cancel or extend timer owned by {owner}",
  "fix": "Only the actor that scheduled a timer may cancel or extend it. Use the timer_id you obtained from schedule_timer.",
  "docs_url": "https://docs.cowboy.inc/errors/E1503"
}
```

***

> [card] [All Error Codes](https://docs.cowboy.inc/errors/overview.md)
>
> View the complete error code reference


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