The latest SonicWall signed certificate is using SHA256, which isn't supported by default on Windows 7. The Microsoft KB3033929 adds SHA-2 code signing support for Windows 7 and Windows Server 2008 R2 - version: 1.0.
CAUTION: This update is not available for Windows Server 2003, Windows Vista, Windows Server 2008 or prior versions as such they will not work for NetExtender 8.0.241 or later.
Uninstall SonicWall NetExtender. Click Start | Control Panel | Programs | Uninstall a program | Right click SonicWall NetExtender | Click Uninstall/change.
Delete the following path: C:\Program Files (x86)\SonicWall\SSL-VPN\NetExtender.
Re-install NetExtender. The Install process should complete correctly. Verify everything is now working with NetExtender on the system. If this does not fix your issue please reach out to our Support team for additional assistance and let them know you used NetExtender 8.6.265 and the issue persists.
There are two ways to contact technical support:
1. Online: Visit mysonicwall.com. Once logged in select Resources & Support | Support | Create Case.
2. By phone: please use our toll-free number at 1-888-793-2830. Please have your SonicWall serial number available to create a new support case.