I use Notes 3.1.1 and NC 17.0.2. How can I migrate all the notes an a NC installation into another NC installation? The simple way in Calendar or Contacts to do it by export/import obviously does not exist in Notes - unless it’s hidden from my eyes.
Afaik, all created notes are stored in a Notes folder within the Nextcloud file structure. Therefore you can select that folder, click on the three dots (…) and choose download.
Alternatively you can go to the Nextcloud data directory and copy the files on the command line to the new server.
cd /<nextcloud-datadirectory>/<user>/files/Notes ...