Failed to write session data (user) on localhost - php

Question

On win10 pro 64 I use WAMP Server 3.0.6 64bit for joomla localhosting
So, there are two virtual hosts in server: interopt and gmdb
The first works perfect
but when trying to run the second it responses with
Warning: session_write_close(): Failed to write session data (user). Please verify that the current setting of session.save_path is correct (f:/wamp64/tmp) in F:\wamp64\www\gmdb\libraries\joomla\session\handler\native.php on line 194
Session_save_path looks correct while it's really placed on f:/wamp64/tmp (folder has read/write permissions
On 194 line of native.php is
session_write_close();
I use php version 7.0.10 (but the same problem appears when turnning on 5.6.25 too)
virtual hosts seem work perfect and host file too
Any idea? Could you please help?
My virtual hosts
<VirtualHost *:80>
ServerName localhost
DocumentRoot f:/wamp64/www
<Directory "f:/wamp64/www">
Options +Indexes +Includes +FollowSymLinks +MultiViews
AllowOverride All
Require all granted
</Directory>
</VirtualHost>
<VirtualHost *:80>
ServerName interopt
DocumentRoot f:/wamp64/www/interopt
<Directory "f:/wamp64/www/interopt">
Options +Indexes +Includes +FollowSymLinks +MultiViews
AllowOverride All
Require all granted
</Directory>
</VirtualHost>
<VirtualHost *:80>
ServerName gmdb
DocumentRoot f:/wamp64/www/gmdb
<Directory "f:/wamp64/www/gmdb">
Options +Indexes +Includes +FollowSymLinks +MultiViews
AllowOverride All
Require all granted
</Directory>
</VirtualHost>