---
page_type: error
code: 40139
message: "40139: Failed to issue Conference Instruction due to invalid ActivitySid"
level: ERROR
product: TaskRouter
---

## Description

Conference Instruction requires a valid `post_work_activity_sid`

### Possible Causes

- The provided `post_work_activity_sid` is invalid or no longer exists in the operating Workspace.

### Possible Solutions

- Ensure that a valid ActivitySid is provided in the `post_work_activity_sid` property in the Worker's attributes or request parameters.

#### Example

```
{
	"instruction": "conference",
	"to": "client:alice",
	"from": "bob",
	"post_work_activity_sid": "WA0123456789abcdef0123456789abcdef"
}
```