There are 3 configuration files in cuteeditor installation,
CuteSoft_Client\CuteEditor\Configuration\Security\Admin.config
CuteSoft_Client\CuteEditor\Configuration\Security\Default.config
CuteSoft_Client\CuteEditor\Configuration\Security\Guest.config
Please do the following test:
1. Modify "filenamePattern", restore it to the default value in all of these 3 files. Does it work fine?
2. If you remove the following line, does it work fine?
<security name="filenamePattern">^[a-zA-Z0-9\._\s-\#]+$</security>
3. When you upload one file every time, test it several times with different file, does every file have this issue or only some specific file have this issue?
Regards,
Eric