Nespecifikovaný error

Zdravím,
po instalaci pluginu Ultimate Member mi začala stránka vyhazovat tento error.
Absolutně nevím co to je, jak s tím pracovat. V PHP ani v něčem podobným se vůbec nevyznám.
Stránku nelze bez erroru načíst a nejde dělat skoro nic. Nemohu se ani odhlásit.
Děkuju moc

Warning: Use of undefined constant REQUEST_URI – assumed ‚REQUEST_URI‘ (this will throw an Error in a future version of PHP) in /data/web/virtuals/242528/virtual/www/domains/naplanujsvujtrip.cz/wp-content/themes/oceanwp/functions.php on line 73

Warning: Cannot modify header information – headers already sent by (output started at /data/web/virtuals/242528/virtual/www/domains/naplanujsvujtrip.cz/wp-content/themes/oceanwp/functions.php:73) in /data/web/virtuals/242528/virtual/www/domains/naplanujsvujtrip.cz/wp-login.php on line 496

Warning: Cannot modify header information – headers already sent by (output started at /data/web/virtuals/242528/virtual/www/domains/naplanujsvujtrip.cz/wp-content/themes/oceanwp/functions.php:73) in /data/web/virtuals/242528/virtual/www/domains/naplanujsvujtrip.cz/wp-login.php on line 512

Warning: Cannot modify header information – headers already sent by (output started at /data/web/virtuals/242528/virtual/www/domains/naplanujsvujtrip.cz/wp-content/themes/oceanwp/functions.php:73) in /data/web/virtuals/242528/virtual/www/domains/naplanujsvujtrip.cz/wp-includes/functions.php on line 6029

Warning: Cannot modify header information – headers already sent by (output started at /data/web/virtuals/242528/virtual/www/domains/naplanujsvujtrip.cz/wp-content/themes/oceanwp/functions.php:73) in /data/web/virtuals/242528/virtual/www/domains/naplanujsvujtrip.cz/wp-includes/pluggable.php on line 961

Warning: Cannot modify header information – headers already sent by (output started at /data/web/virtuals/242528/virtual/www/domains/naplanujsvujtrip.cz/wp-content/themes/oceanwp/functions.php:73) in /data/web/virtuals/242528/virtual/www/domains/naplanujsvujtrip.cz/wp-includes/pluggable.php on line 962

Warning: Cannot modify header information – headers already sent by (output started at /data/web/virtuals/242528/virtual/www/domains/naplanujsvujtrip.cz/wp-content/themes/oceanwp/functions.php:73) in /data/web/virtuals/242528/virtual/www/domains/naplanujsvujtrip.cz/wp-includes/pluggable.php on line 963