CPM stops working with the "Lost connection to license server" error

Background:

When running CPM "Free Trial & BYOL Edition", It needs to connect to our license server and you may experience the below error:

• The system identified issues and will stop backing up. This could be due to a downgrade of an existing server or expiration of license.
  
• Lost connection to license server
  

Troubleshooting:

Usually, this problem will get resolved by itself in a few minutes - please refresh the browser in 15 minutes.

If the problem persists, please connect to the CPM Server over SSH (using user "cpmuser" and your assigned EC2 key) and run this command

1. wget --no-check-certificate https://license.n2ws.com/
   

You should get this result:

If you do not get response "200 OK", something is blocking the CPM Server instance - maybe it's the VPC settings, maybe it's a proxy or gateway.

If you have a proxy, You can also test using this command: 

1. wget -e use_proxy=yes -e http_proxy=http://proxyadress:port https://license.n2ws.com --no-check-certificate
   

In addition, we have seen before that sometimes this may happen due to DNS issues, for example if DNS changes and the proxy address itself cannot be resolved.

You have in this link few suggestion on how to test: https://www.golinuxcloud.com/commands-check-if-connected-to-internet-shell/#3_DNS_lookup_using_nslookup,_host_etc

Problems can still appear even when the wget test shows success, sometimes this failure is random in nature as the result of an advanced gateway/firewall software or web traffic filter appliance.

In some cases when the connection is blocked in this random manner, you may see the following in CPM server logging:

ERROR:  get_license_status_from_license_server(.\cpmserver\cpm\compliance_utils.py:531)  failed calling url: Exception: HTTP Error 403: Forbidden.

<title>The URL you requested has been blocked</title>
....

<h1>XXXXXX Web Filtering</h1>

....

<h3>Web Page Blocked!</h3>

....

<p>The page you have requested has been blocked, because the URL is
banned.</p>
        URL: https://license.n2ws.com/<br />
      

Thanks for reading this KB,

N2WS Support Team.

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