> For the complete documentation index, see [llms.txt](https://docs.high-mobility.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.high-mobility.com/changelog/readme/january-2026.md).

# January 2026

### 2026-01-19

#### - Breaking Change: MQTT V2 Client ID Authentication Requirement (Effective 26.01.2026 14:00 UTC)

Starting January 26th, we will enforce authentication for MQTT connections based on the Client ID.

Required Client ID Format: The Client ID must adhere to the following structure: 

```
<project-id>-<instance>-<random string>
```

**Example**:

If you are subscribing to the topic: `$share/d13c5fe3-423d-44ac-bbac-f5e1f110b0a0/sandbox/level13/d13c5fe3-423d-44ac-bbac-f5e1f110b0a0`

You must use a Client ID such as: `d13c5fe3-423d-44ac-bbac-f5e1f110b0a0-sandbox-s12123`

mosquitto\_sub Example:&#x20;

```
mosquitto_sub --host mqtt-v2.high-mobility.com --port 8883 --qos 1
--topic '$share/d13c5fe3-423d-44ac-bbac-f5e1f110b0a0/sandbox/level13/d13c5fe3-423d-44ac-bbac-f5e1f110b0a0'
--id d13c5fe3-423d-44ac-bbac-f5e1f110b0a0-sandbox-xwdsad --disable-clean-session
--cert client_crt.pem --key client_key.pem --cafile ca_crt.pem --verbose --debug 
```

**Need Assistance?**&#x20;

If you are unsure of the correct format, please visit our console. The new required snippet is available in the MQTT V2 sections.

<figure><img src="https://1424261174-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FZzlrCfp27GnthRoJhwlK%2Fuploads%2FyF1UYnIPecz51V6cxrVD%2Fmqtt-v2-snippet.png?alt=media&amp;token=f301042f-6d1f-439e-9574-76b0b4cefa29" alt=""><figcaption></figcaption></figure>


---

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