Running the Plesk Daily Maintenance Task or clicking the Retrieve Keys button (at Tools&Settings > License Management ) fails with the following error:
curl: (7) Failed to connect to 2001:4168:1236::80: Network is unreachable
In the user interface, the following error may appear:
cURL error description: Failed to connect to ka.plesk.com port 5224: Network unreachable(7)
cURL bug. Inappropriate handling of interface availability:
cURL tries to use IPv6 even though it is not configured properly (the IPv6 network is unreachable) and does not retry with IPv4 after a failure.
IPv6 stack misconfiguration:
The IPv6 stack is configured but is not working (cannot be used to transmit/receive data). As a result, cURL fails when trying to connect via IPv6.
In any system, you can force cURL to drop its name resolution attempts by specifying the address of KA server in the appropriate
/etc/hostsfor Linux and
Note: Use it at your own risk!
On Linux, you can try to disable the IPv6 protocol by adding the following lines to
net.ipv6.conf.all.disable_ipv6 = 1 net.ipv6.conf.default.disable_ipv6 = 1 net.ipv6.conf.lo.disable_ipv6 = 1
Alternatively, execute the following command:
echo 1 > /proc/sys/net/ipv6/conf/all/disable_ipv6
On Windows, IPv6 tunneling interfaces can be disabled with the following commands:
netsh interface ipv6 6to4 set state disabled netsh interface teredo set state disabled
IPv6 for a real interface can be disabled via the user interface:
You can also set the
curloption when using it from PHP, as follows:
curl_setopt($ch, CURLOPT_IPRESOLVE, CURL_IPRESOLVE_V4 );