Hi,
unfortunately mysql has not a verbose error logging, so one should be on your instance to investigate further.
One question: what about sql_mode configuration parameter and collation type/character set of your db?

Search the forum. You will find tons if topics regarding sql_mode directive

Please have a look in your web server logs.

You should know how to configure your web server to store correctly PHP errors.
I can only suggest to get rid of IIS (and Windows as well) and switch to a LAMP environment.

On a standard Windows Server, IIS log files are found at %SystemDrive%\inetpub\logs\LogFiles by default

Hi the error is in apache log.
Find it and post it here.

Esatto, è un'informazione.

Quale sarebbe il messaggio di errore?

It sounds definitely like a bug!

La pagina non è bianca, manca il content.
Confermo, si tratta di un bug.