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Cannot Contact License Server

When an end-user encounters a “Cannot contact license server” error, it typically means the application is unable to establish a secure connection with KEYZY’s API to validate the license. This is often due to local network restrictions, security software, or system configurations.

Start Here: Check Your Client Library Version

Most network reports we receive come from applications built with a client library older than 1.9.0. Those versions report every network problem as a single CONNECTION_ERROR, which leaves both you and us guessing. From 1.9.0 onwards, a failed call returns a status that names the cause — and rebuilding also picks up every networking improvement released since your current version.

Before investigating anything else:

  1. Download the latest C++ Client Library and rebuild your application.
  2. Add cases for the network statuses listed in the C++ License Status Codes reference. The change is additive — your existing switch (status) code keeps compiling and behaving exactly as before.
  3. Send the affected customer a new build.

The next failed attempt will then tell you which of the cases below you are dealing with, instead of a generic error.

Reading the Status

Once your build returns a specific status, use it to go straight to the right check:

StatusWhat it usually meansWhere to look
NETWORK_DNS_FAILEDNo internet connection, or DNS blocked on that networkInternet Connectivity
NETWORK_REFUSEDFirewall or antivirus blocking outbound HTTPSFirewall & Antivirus Allowlisting
NETWORK_TIMEOUTFirewall, or a proxy silently dropping the connectionFirewall & Antivirus Allowlisting, Corporate Network Restrictions
NETWORK_PROXY_REQUIREDThe network requires an authenticated proxyCorporate Network Restrictions
NETWORK_TLS_FAILEDSecurity software inspecting HTTPS traffic, or a wrong system clock on the deviceFirewall & Antivirus Allowlisting, and the SSL note under How to Analyze the Output
NETWORK_HOSTS_TAMPEREDapi.keyzy.io resolves to a local address on that machineThe hosts file note under How to Analyze the Output
CONNECTION_ERRORThe build is older than 1.9.0, or the cause is not one of the aboveWork through the whole page

Standard Troubleshooting

Before diving into logs, please verify the following common causes:

  1. Internet Connectivity: Ensure the device has an active and stable internet connection.
  2. Firewall & Antivirus Allowlisting: Security software (Windows Defender, 3rd party Antivirus, or Firewalls) may mistakenly block the connection. Ensure that the software has permission to make outbound connections or that api.keyzy.io is whitelisted on port 443.
  3. Corporate Network Restrictions: If the user is on a corporate or restricted network (e.g., office, university, or VPN), the network administrator may need to explicitly allow access to the keyzy.io domain.
  4. Hardware ID Consistency: Confirm that the user is not running MAC address spoofing software. KEYZY relies on hardware identifiers, and spoofing tools can disrupt the validation process.

Advanced Troubleshooting: Diagnosing Network Issues

If the issue persists — or if the application is an older build that only reports CONNECTION_ERROR — you may need to investigate the specific network response to pinpoint the failure (e.g., DNS resolution failure, SSL handshake blocking, or firewall termination).

Ask your customer to run the following diagnostic command:

For macOS and Linux Users

  1. Open the Terminal app
  2. Copy and paste the following command and press Enter:
curl -v https://api.keyzy.io/v2/status-check
  1. Copy the entire text output and send it to the support team.

For Windows Users

  1. Press the Windows Key, type cmd, and select Command Prompt (do not use PowerShell)
  2. Copy and paste the following command and press Enter:
curl -v https://api.keyzy.io/v2/status-check
  1. Take a screenshot of the result or copy the text and send it to the support team.

How to Analyze the Output

Once you receive the output from your customer, look for the following clues: