Symptoms
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Plesk interface is unresponsive or Plesk shows the message that the license key is expired
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The following error is shown in Plesk and in
/var/log/plesk/panel.logfile:ERR [1] Token validation failed: Can not connect to 'ka.plesk.com' (6:6). Please check connection to 'ka.plesk.com' or contact Plesk support: <a href='https://www.plesk.com/support/' target='_blank'>https://www.plesk.com/support/</a>.; ; KV network error (ka.plesk.com: cURL cannot communicate with license server https://ka.plesk.com/jsonrest/pkp/20/verify-key (): Couldn't resolve host name(6)
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Retrieving the license from CLI fails with one of the following messages:
# plesk bin license --retrieve
Updating Plesk license key:
[2017-11-24 05:18:02] ERR [panel] KeyUpdate Result code: 2 Unspecified error
[2017-11-24 05:18:02] ERR [panel] KeyUpdate Result desc: License key is not prolongated yet
# plesk bin license --retrieve
Updating Plesk license key:
2018-09-02T21:25:04+01:00 ERR (3): KeyUpdate Result code: 2 Network failure
2018-09-02T21:25:04+01:00 ERR (3): KeyUpdate Result desc: Couldn't resolve host name -
Telnet connection to
ka.plesk.comworks correctly:# telnet ka.plesk.com
Trying 195.214.233.80...
Connected to ka.plesk.com.
Escape character is '^]'. -
The next command is executed correctly (Do not mind the error):
# curl https://ka.plesk.com/jsonrest/pkp/20/verify-key
Authorization failed -
DNS records of
ka.plesk.comcannot be resolved against some of the configured nameservers:# cat /etc/resolv.conf
nameserver 203.0.112.2
nameserver 8.8.8.8
# dig ka.plesk.com @203.0.112.2
...
;; connection timed out; no servers could be reached
Cause
DNS server misconfiguration.
Resolution
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Resolve the issue on the side of the DNS server or remove the misconfigured DNS server from the interface settings
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Connect to the server via SSH and reinstall license key manually:
# plesk bin license --install A00000-A00000-A00000-A00000-A00000