The problem seems to be when I set a left icon for a list item.
When I want to remove it I select ‘No icon’ in the list.
Then I export the project on my PC but when I run ‘ionic serve’ I’ve got an error for an InvalidCharacter.
Looking in the HTML file of the page I found:
<ion-icon name="No Icon" item-left></ion-icon>
with a space inside the name attribute.
When I removed the space I solved the error.