1. Do a clean removal and a fresh re-installation of Legacy to fix the LegacyFS.exe error. Please visit Uninstall - how to do a complete and totally clean removal of Legacy. Next visit https://legacyfamilytree.com/download-update to download the latest version of Legacy. If you want to keep your Legacy customizations, please visit Backup - How to backup user customization files (Legacy) for the steps to back them up. (Be aware that sometimes it's the customized settings that are the cause of a problem and restoring the settings may bring the problem back.)
2. Start Legacy Family Tree and click on File on the menu bar and select File Maintenance > Check/Repair and proceed with the repair. If any error messages occur during the Check/Repair process, click No in the error message box so that the repair steps can finish. Do Check/Repair twice if errors are found.
3. Start Legacy FamilySearch and click on File and select File Maintenance > Check and Repair.
4. Try FamilySearch again.