Symptoms

After installation of Zend Optimizer or manual PHP installation Horde webmail stops to work.

The following error is displayed when trying to browse webmail website:

Warning: main(PEAR.php): failed to open stream: No such file or directory in C:\Inetpub\vhosts\webmail\horde\lib\core.php on line 26

Warning: main(): Failed opening 'PEAR.php' for inclusion (include_path='C:\Inetpub\vhosts\webmail\horde\lib;.;./includes;./pear') in C:\Inetpub\vhosts\webmail\horde\lib\core.php on line 26

Warning: main(Log.php): failed to open stream: No such file or directory in C:\Inetpub\vhosts\webmail\horde\lib\Horde.php on line 3

Warning: main(): Failed opening 'Log.php' for inclusion (include_path='C:\Inetpub\vhosts\webmail\horde\lib;.;./includes;./pear') in C:\Inetpub\vhosts\webmail\horde\lib\Horde.php on line 3

Warning: _connect(DB.php): failed to open stream: No such file or directory in C:\Inetpub\vhosts\webmail\horde\lib\Horde\DataTree\sql.php on line 1255

Fatal error: _connect(): Failed opening required 'DB.php' (include_path='C:\Inetpub\vhosts\webmail\horde\lib;.;./includes;./pear') in C:\Inetpub\vhosts\webmail\horde\lib\Horde\DataTree\sql.php on line 1255

Cause

PHP and Zend installers force PHP to use a default configuration file for all applications, but horde uses a special configuration file which is placed to its folder.

Resolution

Please open regedit and clean up the default configuration location by removing the following key:

on x86 servers - HKEY_LOCAL_MACHINE\SOFTWARE\php\IniFilePath
on x64 servers - HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\PHP\IniFilePath

Additional information

Please see also http://kb.swsoft.com/en/975