When Moodle tries to create a new user_picture for a specific user, it checks if the user is missing any field required for creating the user picture. In case that happens, it should show a debugging message indicating the missing field and the user which doesn´t have that field. However, with the last update, that message tries to concatenate the text string to the user object, which results in an exception instead of a simple debugging message.

For more information, the error happens at "/lib/classes/output/user_picture.php" at line 109.