Hi all,

i need to upgrade RC webmail from 1.3.17 LTS to 1.4.14 or better 1.5.6.

Env:
Server Version: Apache/2.4.57 (OS/2) OpenSSL/1.1.1l PHP/7.4.32
Server Built: Apr 8 2023 07:51:12

The php webmail fail at boot with this error:

[25-Jan-2024 14:14:06 Europe/Rome] PHP Fatal error:  Uncaught Error: Call to undefined function mb_regex_encoding() in D:\apache\htdocs\webmail\program\lib\Roundcube\bootstrap.php:87
Stack trace:
#0 D:\apache\htdocs\webmail\program\include\iniset.php(74): require_once()
#1 D:\apache\htdocs\webmail\installer\index.php(43): require('D:\\apache\\htdo...')
#2 {main}
  thrown in D:\apache\htdocs\webmail\program\lib\Roundcube\bootstrap.php on line 87