The theme name may contain only alphanumeric symbols and underscore (A-z, 0-9, '_').

Hello,

Do you have theme installed on your host? In this case please check it via any FTP client, that the theme is installed at the location /path_to_wordpress/wp-content/themes/
where /path_to_wordpress/ is the location of your WordPress installation on the server. Make sure there is no extra subfolder with the same or similar name inside /themes. If there is some confusion, try to remove the previous theme, then re-export and install the theme by following this article:
http://answers.themler.com/articles/3624/how-to-install-wordpress-theme

Sincerely,
Nettie,
BillionDigital Team

ok in effetti il tema era contenuto in un'altra cartella:
wp-content/themes/ciao/ciao

ma ora togliendo la cartella e facendo wp-content/themes/ciao funziona!

grazie..

Hi,

You're welcome.
Please let us know if you have any other questions/issues.

Thank you,
Themler Team

Ciao! The error you’re seeing happens because WordPress requires theme names to contain only alphanumeric characters and underscores. Even if your template is called “ciao,” it’s important to make sure the folder names and the Theme Name in style.css match exactly and follow the allowed format. So, renaming the folders to something like ciao_theme and updating the Theme Name accordingly should solve the problem. Also, double-check that there are no spaces or special characters in any of the theme files or folders. If you’re interested in exploring advanced customization options or managing root access for testing themes safely, you might want to check out magisk alpha zip, it offers powerful features that can help enhance your Android experience while experimenting with different apps.