Error Call to a member function addUser() on null

Error thrown with message "Call to a member function addUser() on null"

Stacktrace:
#4 Error in /var/www/html/admin/modules/userman/Userman.class.php:1875
#3 FreePBX\modules\Userman:addUserByDirectory in /var/www/html/admin/modules/userman/Userman.class.php:440
#2 FreePBX\modules\Userman:doConfigPageInit in /var/www/html/admin/libraries/BMO/GuiHooks.class.php:290
#1 FreePBX\GuiHooks:doBMOConfigPage in /var/www/html/admin/libraries/BMO/GuiHooks.class.php:252
#0 FreePBX\GuiHooks:doConfigPageInits in /var/www/html/admin/config.php:445

I can't add new user, this issue is in 15.0.50 version but the 15.0.49 userman module doesn't have problem. I tried do it on different version of php (php5.6, 7.2 and 7.3)