Hi,
Your version is past EOL. You should upgrade to either the latest version or the current LTS at your earliest convenience. Your upgrade path is:
9.4 → 9.9 → 10.0 (last step optional)
You may find the Upgrade Guide helpful. If you have questions about upgrading, feel free to open a new thread for that here.
Regarding your question, you may find this guide helpful: Troubleshooting .NET code coverage import.
HTH,
Ann