---
page_type: error
code: 50408
message: "50408: Invalid participant proxy address"
level: ERROR
product: Programmable Chat
---

## Error - 50408

### Conversations: Invalid participant proxy address

An invalid participant proxy address was supplied.

#### Possible Causes

- Participant MessagingBinding.ProxyAddress parameter provided with the request is not a valid conversation proxy address.

#### Possible Solutions

- Check that the length of MessagingBinding.ProxyAddress parameter does not exceed 256 characters.
- Ensure that MessagingBinding.ProxyAddress parameter contains an address with valid syntax (e.g. SMS phone numbers must follow [E.164 format](/docs/glossary/what-e164)).