Could not load file or assembly 'UiPath.Excel, Version=, Culture=neutral, PublicKeyToken=null'. The system cannot find the file specified

Try first to upgrade all dependencies to the latest version in the project.
Close Studio.
Go to the folder where the packages are downloaded → %userprofile%\.nuget and rename the packages folder to packages_backup.
Reopen the Main.xaml or project.json in UiPath Studio.

Let us knot if this helped.