In Windows 10 v1607 (Redstone 1) and later, Microsoft decided to convert the legacy Sticky Notes program to a UWP app (Universal Windows Platform), and this is what we are using currently on Windows 10.
The classic Sticky Notes store the data in a .snt file whereas the current Sticky Notes app stores the data in a .sqlite file.
To convert old Sticky Notes StickyNotes.snt data file to the new Sticky Notes plum.sqlite format do the following:
• On your Windows 10 machine, close Sticky Notes.
• Now open Settings > Apps > Sticky Notes > Advanced Options. Press the Reset button. The app will be reset to default, and all app data will be deleted as well.
• Locate the legacy Sticky Notes data %AppData%\Microsoft\Sticky Notes
• Rename the data file StickyNotes.snt to ThresholdNotes.snt
• Do not open Sticky Notes app now. Instead, open File Explorer and navigate to the following folder: %LocalAppData%\Packages\Microsoft.MicrosoftStickyNotes_8wekyb3d8bbwe\LocalState\Legacy
• Copy the DB to the new location Copy ThresholdNotes.snt to %LocalAppData%\Packages\Microsoft.MicrosoftStickyNotes_8wekyb3d8bbwe\LocalState\Legacy
NOTE: If the Legacy folder does not exist, you will need to create this folder here in the LocalState folder and then place the ThresholdNotes.snt file from your older Windows system here in the Legacy folder.