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Expiration of Let’s Encyrpt – DST Root CA X3 (September 2021)

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At the end of September, the DST Root CA X3 expired ( ). This root CA is used by devices to authenticate endpoints.

Since 07/14/2021, will automatically update CA certificates on devices with the new ISRT Root CA. Devices connected before 07/14/2021 and not rebooted or connected to between 07/14/2021 and 09/31/2021 may still experience problems.
Even PLCnext controllers with firmware older than 2021.6 may experience problems. It is generally recommended to always use an up-to-date firmware for security reasons.


If one of the mentioned cases applies to you, you have the possibility to reconnect your PLCnext controller to the Proficloud with the following steps:

  1. Get access to the file system of the controller. Use for example WinSCP
  2. Replace the file /opt/plcnext/projects/Default/Services/ProfiCloudV3/ca with the following file
  3. Rename the file ca.crtto ca
  4. Reboot the controller


If your controller is connected, you can simply update the controller via the Device Management Service to the newer firmware version 2021.07.01. The update to this version fixes the certificate issue.
If the device has still connection issues please contact us.


There will not be this issue with ImpulseCheck devices.