Plesk extension key has expired, however Plesk+paid add-on license for KernelCare in Tools and Settings > License Management > Additional Licenses is active. In the extension's interface following message exists:
The following messages may be sent to Plesk administrator:
Mail subject: Cron <root@example> /usr/bin/kcarectl --auto-update
Message: The IP 203.0.113.2 was already used for trialing on 2017-05-16
No handlers could be found for logger "kcare"
The following command results in an output:
# kcarectl --license-info
Your trial license for the IP 203.0.113.2 expired on 2017-05-15
Following error may appear in /usr/local/psa/admin/logs/panel.log:
DEBUG [extension/kernelcare-plesk] [58abc79251960] Starting: '/usr/local/psa/admin/bin/modules/kernelcare-plesk/kcare_plugin_utility.sh' 'plugin-info', stdin:
INFO [panel] Session 51e8fedc51ac87d7ce183ea65496e408 was not saved: not modified DEBUG [extension/kernelcare-plesk] [58abc7934754e] Finished in 0.56546s, Error code: 3, stdout: Key limit reached
DEBUG [extension/kernelcare-plesk] [5937d2b106e27] Finished in 2.39585s, Error code: 0, stdout: --START--
Your trial license for the IP 203.0.113.2 expired on 2017-04-30
Kernel Care key was installed on more than 1 server. KernelCare generates a unique token once the license was first time used for activation. That's why the activation will not work if a license is used on more than 1 server.
Contact KernelCare support for assistance