Extensions Catalog in Plesk is not accessible: Failed connect to ext.plesk.com:443; No route to host

Symptoms

• On a Plesk for Linux server, the menu Extensions is not available:

  Internal server error

• The following error in logged to the file /var/log/plesk/panel.log:

  ERR [extension/catalog] Failed connect to ext.plesk.com:443; No route to host

• Manual connection to ext.plesk.com from the server console fails:

  # curl -vvv https://ext.plesk.com
  * About to connect() to ext.plesk.com port 443 (#0)
  * Trying 195.181.175.6...
  * No route to host
  * Failed connect to ext.plesk.com:443; No route to host
  * Closing connection 0
  curl: (7) Failed connect to ext.plesk.com:443; No route to host

• The hostname ext.plesk.com resolves to the IP address different from the one to which the connection was performed:

  # host ext.plesk.com
  ext.plesk.com is an alias for 1648825949.rsc.cdn77.org.
  1648825949.rsc.cdn77.org has address 89.187.164.8

Cause

The record in the file /etc/hosts points hostname ext.plesk.com to the wrong IP address.

Resolution

1. Connect to the server using SSH.

2. Open the file /etc/hosts for editing.

3. Comment out the line(s) contaiting ext.plesk.com by putting the symbol # at the beginning of the line, e.g.:

   #195.181.175.6 ext.plesk.com