Hi quisella,
You can modify the security policy file toprevent this character.
Please open CuteSoft_Client\CuteEditor\Configuration\Security\Default.config
Navigate to:
<security name="filenamePattern">^[a-zA-Z0-9\._\s-\#]+$</security>
change to:
<security name="filenamePattern">^[a-zA-Z0-9\._\s-]+$</security>
Regards,
Ken