: Some users have successfully triggered the registration box by running the installer or the program in Windows 95 compatibility mode (even on newer versions of Windows), then switching back once registered.
Instead of using third-party patchers which may contain malware, try these manual fixes: patcher for sony vegas pro 9 and 10 fix
Finding a reliable "patcher" or fix for legacy software like Sony Vegas Pro 9 and 10 can be challenging, as these versions were released before MAGIX acquired the Vegas line in 2016. Users often encounter registration errors or "server not found" messages when trying to activate older installations. Common Activation and Loading Issues : Some users have successfully triggered the registration
: Always right-click the application and select Run as Administrator to ensure it has the necessary permissions to write activation data to your drive. Risks of Third-Party "Patchers" Common Activation and Loading Issues : Always right-click
: If your browser cannot contact the registration server, you may be able to use the "alternative" method offered by the software to enter an Authentication Code manually.
: If you've entered the wrong serial key or have conflicting data, uninstall the software and manually delete leftover license files in the system registry at HKEY_CURRENT_USER\Software\Sony and your %AppData%\Sony folders.
: Sony-era licenses often had a limited number of activations. If you hit a "no more" barrier, you may need to contact VEGAS Support to request an activation limit reset. Safe Technical Fixes for Legacy Vegas Pro