When you try to import a file in Elements Organizer, you get the following error message:
This file cannot be imported due to unknown error and added to the blocked media list
This happens because the media file is corrupt or has encountered some unknown issue. The import of this file caused the application to crash once before and it has been blocked for import this time.
Entries for the media files added to the blocked media list can be found in BlockListedPaths.txt file present at the below location:
Windows: C:\Users\<username>\AppData\Roaming\Adobe\Elements Organizer\19.0\Organizer\ BlockListedPaths.txt
macOS: /Users/<username>/Library/Application Support/Adobe/Elements Organizer/19.0/Organizer/ BlockListedPaths.txt
If you wish to try importing the file again, you can quit the application, delete the entry of the blocked media file from .txt file at the mentioned path and try re-importing after relaunching the application. If the file is corrupt, it will again be added to the blocked list on re-importing.