Не открывается админка

Всем привет, возникла проблема со страницей.
Не открывается админка.

Первый раз с таким сталкиваюсь, в чем может быть причина?

Лог с ошибками:

staff-parfum.ru [Wed Oct 21 23:08:42 2020] [warn] [pid 15339] sapi_apache2.c(351): [client 46.242.14.140:45660] PHP Warning:  Cannot modify header information - headers already sent by (output started at /home/c/cb85560/staff-parfum/public_html/wp-content/themes/staff-theme/functions.php:1) in /home/c/cb85560/staff-parfum/public_html/wp-includes/pluggable.php on line 1299
staff-parfum.ru [Wed Oct 21 23:13:18 2020] [warn] [pid 4879] sapi_apache2.c(351): [client 51.68.172.59:39052] PHP Warning:  Cannot modify header information - headers already sent by (output started at /home/c/cb85560/staff-parfum/public_html/wp-content/themes/staff-theme/functions.php:1) in /home/c/cb85560/staff-parfum/public_html/wp-login.php on line 521
staff-parfum.ru [Wed Oct 21 23:13:18 2020] [warn] [pid 4879] sapi_apache2.c(351): [client 51.68.172.59:39052] PHP Warning:  Cannot modify header information - headers already sent by (output started at /home/c/cb85560/staff-parfum/public_html/wp-content/themes/staff-theme/functions.php:1) in /home/c/cb85560/staff-parfum/public_html/wp-login.php on line 537
staff-parfum.ru [Wed Oct 21 23:13:18 2020] [warn] [pid 4879] sapi_apache2.c(351): [client 51.68.172.59:39052] PHP Warning:  Cannot modify header information - headers already sent by (output started at /home/c/cb85560/staff-parfum/public_html/wp-content/themes/staff-theme/functions.php:1) in /home/c/cb85560/staff-parfum/public_html/wp-includes/functions.php on line 6270
staff-parfum.ru [Wed Oct 21 23:13:18 2020] [warn] [pid 4992] sapi_apache2.c(351): [client 51.68.172.59:39222] PHP Warning:  Cannot modify header information - headers already sent by (output started at /home/c/cb85560/staff-parfum/public_html/wp-content/themes/staff-theme/functions.php:1) in /home/c/cb85560/staff-parfum/public_html/wp-login.php on line 521
staff-parfum.ru [Wed Oct 21 23:13:18 2020] [warn] [pid 4992] sapi_apache2.c(351): [client 51.68.172.59:39222] PHP Warning:  Cannot modify header information - headers already sent by (output started at /home/c/cb85560/staff-parfum/public_html/wp-content/themes/staff-theme/functions.php:1) in /home/c/cb85560/staff-parfum/public_html/wp-login.php on line 537
staff-parfum.ru [Wed Oct 21 23:13:18 2020] [warn] [pid 4992] sapi_apache2.c(351): [client 51.68.172.59:39222] PHP Warning:  Cannot modify header information - headers already sent by (output started at /home/c/cb85560/staff-parfum/public_html/wp-content/themes/staff-theme/functions.php:1) in /home/c/cb85560/staff-parfum/public_html/wp-includes/functions.php on line 6270
staff-parfum.ru [Wed Oct 21 23:13:18 2020] [warn] [pid 5018] sapi_apache2.c(351): [client 51.68.172.59:39274] PHP Warning:  Cannot modify header information - headers already sent by (output started at /home/c/cb85560/staff-parfum/public_html/wp-content/themes/staff-theme/functions.php:1) in /home/c/cb85560/staff-parfum/public_html/wp-includes/IXR/class-IXR-server.php on line 143
staff-parfum.ru [Wed Oct 21 23:13:18 2020] [warn] [pid 5018] sapi_apache2.c(351): [client 51.68.172.59:39274] PHP Warning:  Cannot modify header information - headers already sent by (output started at /home/c/cb85560/staff-parfum/public_html/wp-content/themes/staff-theme/functions.php:1) in /home/c/cb85560/staff-parfum/public_html/wp-includes/IXR/class-IXR-server.php on line 145
staff-parfum.ru [Wed Oct 21 23:13:18 2020] [warn] [pid 5018] sapi_apache2.c(351): [client 51.68.172.59:39274] PHP Warning:  Cannot modify header information - headers already sent by (output started at /home/c/cb85560/staff-parfum/public_html/wp-content/themes/staff-theme/functions.php:1) in /home/c/cb85560/staff-parfum/public_html/wp-includes/IXR/class-IXR-server.php on line 148

Страница, с которой нужна помощь: [войдите, чтобы увидеть ссылку]