Error message

• Notice: Trying to get property of non-object in user_access() (line 806 of /var/www/html/modules/user/user.module).
• Notice: Trying to get property of non-object in user_access() (line 818 of /var/www/html/modules/user/user.module).
• Notice: Trying to get property of non-object in user_access() (line 819 of /var/www/html/modules/user/user.module).
• Notice: Trying to get property of non-object in user_access() (line 825 of /var/www/html/modules/user/user.module).
• Notice: Trying to get property of non-object in user_access() (line 828 of /var/www/html/modules/user/user.module).
• Notice: Trying to get property of non-object in user_access() (line 806 of /var/www/html/modules/user/user.module).
• Notice: Trying to get property of non-object in user_access() (line 818 of /var/www/html/modules/user/user.module).
• Notice: Trying to get property of non-object in user_access() (line 828 of /var/www/html/modules/user/user.module).
• Notice: Trying to get property of non-object in user_access() (line 806 of /var/www/html/modules/user/user.module).
• Notice: Trying to get property of non-object in user_access() (line 818 of /var/www/html/modules/user/user.module).
• Notice: Trying to get property of non-object in user_access() (line 828 of /var/www/html/modules/user/user.module).