SymptomsAddress book button is missed in horde webmail after Parallels Plesk Panel upgrade to version 9.5.
ResolutionPlease replace the file %plesk_vhosts%\webmail\horde\config\registry.php with the file from the attachment.
Please review article #1802 about hotfix installation procedure.
Once the file registry.php is replaced please execute the following command for upgrading horde database:
"%plesk_dir%\Additional\php\php.exe" -c %plesk_vhosts%\webmail\horde\php.ini %plesk_vhosts%\webmail\horde\turba\scripts\upgrades\2007-06-17_flatten_shares.php