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How to Fix cURL Errors 6 and 28 When Activating a License Key ​

If license activation fails with cURL error 6 or 28, your server cannot complete its connection to api.themeisle.com. These connection errors happen before the license is validated, so they do not mean that your license key is invalid.

cURL errors 6 and 28: Server connection issues ​

cURL error 6, “Could not resolve host,” means your server could not use DNS (the system that looks up a domain name’s network address) to find api.themeisle.com.

cURL error 28 means the request did not finish before it timed out. If the message says “Resolving timed out,” DNS lookup was delayed or failed. A general connection timeout can also be caused by a firewall, proxy, or other outbound network restriction.

Common causes:

  • A server firewall or hosting restriction is blocking outbound HTTPS requests to api.themeisle.com.
  • A security plugin (e.g., Wordfence, iThemes Security) is blocking the outbound connection.
  • A DNS misconfiguration on the server is preventing name resolution.
  • A proxy or other network restriction is preventing the connection from completing.

Steps to fix:

1. Check your security plugin. If you are using Wordfence, iThemes Security, or a similar plugin, check whether its firewall is blocking requests to api.themeisle.com. If it is, add the domain to the allowlist.

2. Check your hosting firewall and network settings. Some managed hosting providers restrict outbound connections. Verify that your server can make outbound HTTPS requests to api.themeisle.com on port 443. If you cannot check this yourself, ask your hosting provider to investigate its firewall, DNS, proxy, and other outbound network restrictions and allow this connection.

3. Check your site's error log. In your hosting control panel or via FTP, open the PHP/server error log and look for entries mentioning cURL error 6, cURL error 28, or api.themeisle.com. Messages about resolving or connecting timing out can help your host identify where the request is failing.

4. Test connectivity from the server. If you have SSH access, run the following command to confirm the server can reach the license endpoint:

bash
curl -I https://api.themeisle.com

A successful response returns HTTP headers. If the command reports Could not resolve host or times out, the server still cannot complete the connection; share the result with your hosting provider.

5. Contact your host. Share the error message and any test results with your hosting provider. Ask them to investigate DNS resolution, firewall and proxy rules, and other outbound network restrictions, and to allow outbound HTTPS access to api.themeisle.com on port 443.

6. Retry license activation. After the connectivity restriction is corrected and your server can reach the license service, try activating your license key again.

📝 Note: These errors affect the license activation request. Your site and the plugin itself continue to work normally while you troubleshoot the connection.

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