roundcube http 500 error.. [Solved]

isp config 3.2.7p1
ubuntu 18.04

there are several e-mail adresses like,

[email protected]
[email protected]
[email protected]
[email protected]

bbb, ccc, ddd is loging in properly via roundcube but aaa is saying http error 500 when I try to login.
I deleted [email protected] account and recreate it but still got http error 500.

 

there is nothing at apache logs, but roundcube logs file are saying theese;

13-Feb-2022 10:36:46 UTC] PHP Warning: strtotime(): Invalid date.timezone value 'Europe\Istanbul', we selected the timezone 'UTC' for now. in /usr/share/roundcube/program/lib/Roundcube/session/db.php on line 109
[13-Feb-2022 10:36:46 UTC] PHP Warning: strtotime(): Invalid date.timezone value 'Europe\Istanbul', we selected the timezone 'UTC' for now. in /usr/share/roundcube/program/lib/Roundcube/session/db.php on line 110
[13-Feb-2022 10:36:46 UTC] PHP Fatal error: Uncaught Exception: DateTime::__construct(): Invalid date.timezone value 'Europe\Istanbul', we selected the timezone 'UTC' for now. in /usr/share/roundcube/program/lib/Roundcube/rcube_user.php:542
Stack trace:
#0 /usr/share/roundcube/program/lib/Roundcube/rcube_user.php(542): DateTime->__construct()
#1 /usr/share/roundcube/program/include/rcmail.php(619): rcube_user->is_locked()
#2 /usr/share/roundcube/index.php(121): rcmail->login()
#3 {main}
thrown in /usr/share/roundcube/program/lib/Roundcube/rcube_user.php on line 542

 

it's related with php-fpm.ini.
I changed this;
date.timezone = Europe\Istanbul
to this;
;date.timezone = Europe\Istanbul
and it started working.

 

Correct syntax is with slash, not backslash:

Code:

date.timezone = Europe/Istanbul