If you are using Windows 10 April 2018 update (version 1803) and attempting to backup Microsoft Edge executable file (MicrosoftEdge.exe) using SyncBack then the backup may fail with the error: 'The file cannot be accessed by the system'. You may receive the same error when trying to copy MicrosoftEdge.exe file manually through a File explorer.
This is due to the new security changes introduced by Microsoft in Windows 10 April 2018 update. Windows prevents access to that file even with the use of Volume Shadow Copy service (VSS).
The only solution is to exclude 'MicrosoftEdge.exe' file from your backup file/folder selections. You can deselect the file from:
Modify > Simple > 'Choose sub-directories and files' settings page