After upgrading the Trailhead site you may have noticed your profile picture is missing. You will need to add your profile picture again.
Here are the steps to add profile picture back on Trailhead:
To change your picture, log into Moodle then click your name in the top right of the screen → Profile → Edit Profile (from the gear icon) and scroll down to the User Picture area. Drag your desired image file into the New Picture box. The file should be a .jpg or .png file format and will be cropped and resized to a 100x100 pixel square automatically.