As it is 2021 now, the Polar Flow Exporter doesn't export your workouts as XML anymore, but as there own JSON scheme for the Polar training sessions. This is so far great, because I have written a converter…
Yes exactly. Thanks for the converter! Here' the tread the my more detailed instructions and info.
forums.garmin.com/.../1447730
https://flow-exporter.ddns.net/index.php?status=1
This worked perfect for me! Export all your polar activities in .tcx-format with this tool (blocks of 180 days per export zip-file). When you specify which period you want to export, don't forget te check the box "importable in Garmin" (or something like that :-) ). Next unpack all your downloaded zip-files to one folder. Garmin allows you to import multiple files at a time, I imported all 400 .tcx-files at once. Went flawless!!!!
As it is 2021 now, the Polar Flow Exporter doesn't export your workouts as XML anymore, but as there own JSON scheme for the Polar training sessions. This is so far great, because I have written a converter for that. Converting this .json-files from the Polar Flow export to state-of-the-art Garmin .fit-files. :) Just upload those FIT files to Garmin after conversion.
https://www.tredict.com/polarjson2fit-converter/