Corrupted .fit file, can't upload to Garmin

Hi! I'm having a trouble with uploading my .fit file to Garmin Connect, it says file is corrupted. I've tried using FIT File Viewer but it showed me one of records is 18 May 1996! I have no idea how to correct it. I've walked 21km and this activity is important for me. I hope someone can help me.

Best regards.