When the extension phpexpress-php-4.3.so is set in php.ini, this problem appears in the webmail:

Required "Array" not specified in DataTree SQL configuration. The file /config/conf.php should contain a $ conf['storage']['params']['Array'] setting.

Did you install phpexpress 1.3.11 or an earlier version? In latter case, please update to 1.3.11 (it's on the site since yesterday).

How to update ??? simply uninstall old version and install new version ? If yes, will not be easier to provide that as a ZIP ?

just replace module, restart web and check phpinfo to make sure new version is there

Ah ok ... so i don't need to re-encode the files ... right ? just the web module that changes ...

Although PhpExpress supports any files encoded with Nu-Coder and previously encoded files will load, the encoder itself may change from version to version and produce more (or less) correct bytecodes. I'd recommend you to re-encode the project and check.
BTW, what's the reason to encode an open-source project?

I don't want to encode horde webmail ... the installation of this extension make a side effect with horde ...

By the way, version 1.3.11 did not fix that problem ...

Can someone that have Horde webmail install on is server and the phpexpress extension install in php.ini tell sme if the webmail works ?

I tried SquirrelMail and it worked well.
I'll check what's up with Horde in a week or less.

something new ?

The problem is replicated. Fix will be available by the end of this week.