Recently I was trying to sync my hiking course from Garmin connect to my Garmin Forerunner 965 and found that it does not work.

After some experiment, I found the issue: the number of courses in my Garmin watch have exceeded the limit. According to a post on Garmin forum, the limit for course number is 100:

have you reached the limit of 100 courses in folder /Courses?

After some verifying work, indeed, the number of courses in my Garmin Forerunner has reached the limit¹. That is why the new course in Garmin connect can not be synced to my watch.

How to delete courses in the Garmin watch

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So the solution is quite simple: just delete some courses in the Garmin watch. There are basically two ways to delete the courses in your watch:

1. You can do it in your watch. When you select and enter a course, in the menu, there is an option to delete the course. However, it seems that you can not delete multiple courses at the same time. You have to delete one by one!
2. Connect your watch to your computer and delete the courses under Garmin/Courses/ folder.

macOS connection issues for Garmin watch

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If you use solution 2, you will have troubles connecting your watch to macOS and seeing the Garmin drive, because macOS does not support MTP (Media Transfer Protocol) natively. You need to install some 3rd party application on your mac to see the Garmin watch drive.

On macOS, we can use the application openMTP to show the Garmin watch drive. Install and open the application, then connect your Garmin watch to your MacBook. You should be able to see the Garmin watch folder on the right side of the openMTP application UI. Then you can delete the courses easily in the UI.