Using FileMaker Pro Advanced > About creating runtime solutions (FileMaker Pro Advanced) > Starting runtime solutions (FileMaker Pro Advanced)
Starting runtime solutions (FileMaker Pro Advanced)
After a user has run the installation program for your runtime application, the files are installed on the user’s hard drive. The solution’s three-character filename extension is registered with the operating system (Windows) or in the system preferences (macOS). This registration allows the operating system to locate and launch the runtime solution if the user double-clicks the primary or auxiliary solution files. If a primary or auxiliary solution file is double-clicked before the runtime application has registered the extension, the runtime application won’t be found.
Important  Your users should start your solution by double-clicking the runtime application icon, not the solution file icon. Double-clicking the icons for the solution or auxiliary files might result in errors, depending on whether there are other copies of the runtime application on their hard disk. If your users have more than one solution on their computers associated with the same three-character extension and they double-click the icon for the solution file, the first solution installed will attempt to open the file, and this might not be the correct application for the specific solutions file.
Runtime application icon
Runtime application. Tell users to double-click this icon to start the runtime application.
Runtime document icon
Solution file
Each time the runtime application is opened, it looks for the primary file that has been bound to it. If the primary file can’t be found, the user is asked to locate the primary file.
Caution your users that they should not rename the primary or auxiliary solution files. If they do, relationships and external scripts may not work properly.
When you make a change to your solution, make sure that your users can import their data into your updated solution. Include a script attached to a button to make it easy for your users to import their data into the new solution files.
Related topics 
About creating runtime solutions (FileMaker Pro Advanced)
Preparing files for a runtime solution (FileMaker Pro Advanced)
Binding files into a runtime solution (FileMaker Pro Advanced)
Naming runtime solutions (FileMaker Pro Advanced)
Distributing runtime solutions (FileMaker Pro Advanced)
Importing data into upgraded runtime solutions (FileMaker Pro Advanced)
Recovering runtime files (FileMaker Pro Advanced)