If you are getting segmentaion fault/blank page for horde in plesk, you can check the following steps
1. Log in to the server shell.
2. Issue the following command:
# mysql -uadmin -p`cat /etc/psa/.psa.shadow` psa -e “replace into misc (param,val) values (’apache_pipelog’, ‘true’);”
3. Rebuild Apache configuration as follows:
# $PRODUCT_ROOT_D/admin/sbin/websrvmng -v -a