First of all. I would appreciate to warn me beforehand before closing a discussion I started.
This discussion is supposed to be not an Garmin express problem. The app you use to put stuff on your watch when you use your PC/laptop is called Garmin Express: 
Today I tried to install a GPX-file from a race with waypoints that I put on the course myself. Apperently the file is not compatible. Then I tried it again without adding my personal waypoints and again it was not compatible. When I download the fit-file and then put it manually on my watch there's no problem. But putting the course on my watch is not why I posted this. The reason why I posted this is to know how I can't get rid of this error mesage. Garmin express is apperently continuing to try and install the file. I got rid of the error message for the first file after trying to install the second file. But I don't seem to be able to get rid of the error message for the second file. Probably I can get rid of this with another incompatible file, but then I'll be stuck with an error message for this one.
PS I already cleaned up the history.
PS Furthermore the error message I'm talking about is an error message that shows up in Garmin Express:
