Unable to open one or few messages in Horde webmail, this error is shown instead of message in new window:
Class 'Math_BigInteger' not found [pid 7517 on line 172 of "/usr/share/psa-pear/pear/php/Horde/Mapi.php"]
Also this error message is shown:
Error when communicating with the server
This is a software issue with internal id PPPM-3090 and it will be fixed in further Plesk updates.
As workaround, install and copy this module to required directory:
# /usr/share/psa-pear/pear/pear install Math_BigInteger
# cp -R /usr/share/pear/Math/ /usr/share/psa-pear/pear/php/