Solutions

• Manually change the file extension from “opml” to “qpopml”.
• Alternatively, convert the OPML file with QuickPlan for iPad and then sync it to the Mac via iCloud Drive.

What happened:

QuickPlan for macOS supports creating a new project by importing from an OPML file. Watch the video

However, you may receive the error message “The document ‘***.opml’ could not be opened. QuickPlan cannot open files of this type” when opening an OPML file.

The error message indicates that macOS does not support sending an OPML file to the QuickPlan app. Because another app has registered the file extension “opml” for a different purpose, preventing other apps from opening the same file type. Since QuickPlan does not have permission to change the macOS setting (QuickPlan runs in the sandboxed environment with limited permission), this is beyond QuickPlan’s control.

macOS controls how an app can open a file:

• When an app is installed, the app tells macOS that a file extension is supported (in this case, QuickPlan must support the .opml file extension). macOS adds the app to the file menu list for the appropriate file extension.
• When a user opens a file with the file extension, macOS checks the registry information and sends the file to the app to open.

In your case, if something is wrong with the registry information for the file extension, macOS will not send the file to QuickPlan and will replace it with the error message. Apps downloaded from the App Store have limited permission that can only register the file extensions to macOS, but no way to control macOS directly.

We can check the apps registered by macOS for a file type:

• Right-click on a file with the .opml extension.
• Click on the menu “Get Info.”
• In the file info dialog, check the “Open with” drop-down list. The default app may prevent other apps from opening the files with the same extension.