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Why don't I get an SSL connection to the PRTG web interface? "This webpage is not available."



When I try to connect to the PRTG web interface (PRTG 8), my browser (Google Chrome) shows the error message stated below.

This message only occurs when I set the web server to use secure connections on port 443. Using insecure connections on port 80 works without issues.

What can I do to connect to the the web interface with SSL encryption?

Google Chrome SSL Settings


This webpage is not available.

The webpage at https://x.x.x.x/index.htm might be temporarily down or it may have moved permanently to a new web address.

Below is the original error message

Error 101 (net::ERR_CONNECTION_RESET): Unknown error.


In Firefox, this error may be called ssl_error_ssl_disabled

connection http prtg reghack registry ssl unavailable web-interface

Created on Nov 12, 2010 2:49:44 PM by  Daniel Zobel [Product Manager]

Last change on Sep 19, 2012 7:07:37 AM by  Daniel Zobel [Product Manager]

1 Reply

Accepted Answer



Important notice: The information in the article below is outdated. With PRTG version 14.4.12 we implemented various security enhancements, including stronger encryption. For details, please see the following articles:

This article applies to PRTG Network Monitor 8.1.2 through 13.x.8

Enhanced Security

As of PRTG build, the default SSL version for secure connections is set to SSL v3. Before, connections could be established with SSL v2. As this is regarded a potential security risk, PRTG's web server does not accept SSL v2 connections in current versions.

Check Browser Settings

Please make sure that your browser is set to use SSL v3. This can be an issue with older browsers. But also in Google Chrome, for example, there might be a setting enabled which sets the browser to connect via SSL 2.0.

If you experience problems connecting with Chrome, please disable SSL v2 in its options. For more information, please see: SSL for web interface does not work with Google Chrome

Allow SSLv2 Connections for PRTG

However, if you want to explicitly enable SSL v2 connections for the PRTG web server, you can add a new value to the Windows registry.

Caution: Please backup your system before manipulating the Windows registry! Using SSL v2 might be a security risk.

Step 1

On the system running the PRTG core server, please stop the core server Windows service. If you don't, your changes might not be saved. You can stop the service using the PRTG Administrator program (Service Start/Stop tab).

Step 2

  • On the system running the PRTG core server, open the registry editor.
  • For a 64-Bit Windows system, go to HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Paessler\PRTG Network Monitor\Server\Webserver\
  • For a 32-Bit Windows system, go to HKEY_LOCAL_MACHINE\SOFTWARE\Paessler\PRTG Network Monitor\Server\Webserver\

Note: If you run a deprecated PRTG version V7/V8, you will this version number in each path above.

Step 3

  • Add a new DWORD value with the name AllowSSLV2.
  • Set this to 1 to change allow SSL v2 connections for the PRTG web server.

Step 4

On the system running PRTG core server, please use the PRTG Administrator program (Service Start/Stop tab) to restart the core server Windows service.

See Also

How can I access PRTG through Citrix NetScaler?

Created on Nov 15, 2010 1:21:29 PM by  Daniel Zobel [Product Manager]

Last change on Mar 30, 2015 4:41:10 PM by  Gerald Schoch [Paessler Support]

Disclaimer: The information in the Paessler Knowledge Base comes without warranty of any kind. Use at your own risk. Before applying any instructions please exercise proper system administrator housekeeping. You must make sure that a proper backup of all your data is available.