# 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: ``` -- ``` **Example**: If you are subscribing to the topic: `$share/d13c5fe3-423d-44ac-bbac-f5e1f110b0a0/sandbox/level13/d13c5fe3-423d-44ac-bbac-f5e1f110b0a0` You must use a Client ID such as: `d13c5fe3-423d-44ac-bbac-f5e1f110b0a0-sandbox-s12123` mosquitto\_sub Example: ``` mosquitto_sub --host mqtt-v2.high-mobility.com --port 8883 --qos 1 --topic '$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?** If you are unsure of the correct format, please visit our console. The new required snippet is available in the MQTT V2 sections.
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