Problem with user registration OJS 2.4.8.3

Hello all,

Here’s the active installation URL:
http://encontrodemuseologia.fci.unb.br

It’s a XAMPP server on a Windows machine.
When registering a user, system seems to be executing twice the registration form, as it displays messages regarding login, email and the such already existing on the system.

Emails are being sent and user is actually registered. I thought there would be a need to validate email validation prior to completing the registration, but email is sent.

Any ideas?

There’s nothing significant AFAIK in apache’s error log. Here’s the log for today (july 12th):

[Thu Jul 12 00:23:24.813414 2018] [cgi:error] [pid 5104:tid 1628] [client 35.237.75.180:38126] AH02811: script not found or unable to stat: C:/xampp/htdocs/dnscfg.cgi
[Thu Jul 12 00:28:17.016539 2018] [authz_core:error] [pid 5104:tid 1628] [client 61.160.221.44:32809] AH01630: client denied by server configuration: C:/xampp/phpMyAdmin/scripts
[Thu Jul 12 02:14:24.157164 2018] [:error] [pid 5104:tid 1640] [client 1.222.38.195:34470] PHP Notice: Undefined index: HTTP_HOST in C:\xampp\htdocs\index.php on line 7
[Thu Jul 12 02:35:38.000914 2018] [:error] [pid 5104:tid 1640] [client 31.184.194.109:62586] PHP Notice: Undefined index: HTTP_HOST in C:\xampp\htdocs\index.php on line 7
[Thu Jul 12 03:08:25.438414 2018] [:error] [pid 5104:tid 1640] [client 62.122.50.21:44206] PHP Notice: Undefined index: HTTP_HOST in C:\xampp\htdocs\index.php on line 7
[Thu Jul 12 03:42:14.422789 2018] [:error] [pid 5104:tid 1640] [client 84.1.26.179:56630] PHP Notice: Undefined index: HTTP_HOST in C:\xampp\htdocs\index.php on line 7
[Thu Jul 12 05:06:10.297789 2018] [:error] [pid 5104:tid 1640] [client 69.246.211.162:48362] PHP Notice: Undefined index: HTTP_HOST in C:\xampp\htdocs\index.php on line 7
[Thu Jul 12 05:16:14.657164 2018] [:error] [pid 5104:tid 1640] [client 196.52.43.113:6666] PHP Notice: Undefined index: HTTP_HOST in C:\xampp\htdocs\index.php on line 7
[Thu Jul 12 05:50:29.625914 2018] [:error] [pid 5104:tid 1640] [client 76.8.252.194:22967] PHP Notice: Undefined index: HTTP_HOST in C:\xampp\htdocs\index.php on line 7
[Thu Jul 12 08:22:18.313414 2018] [:error] [pid 5104:tid 1600] [client 107.155.132.169:55723] PHP Notice: Undefined index: HTTP_HOST in C:\xampp\htdocs\index.php on line 7
[Thu Jul 12 11:31:04.563414 2018] [:error] [pid 5104:tid 1600] [client 107.155.132.169:48480] PHP Notice: Undefined index: HTTP_HOST in C:\xampp\htdocs\index.php on line 7
[Thu Jul 12 11:46:00.797789 2018] [:error] [pid 5104:tid 1600] [client 31.184.194.109:62586] PHP Notice: Undefined index: HTTP_HOST in C:\xampp\htdocs\index.php on line 7