Freeze after registering

[Tridz]

SMF 2.0.12
After a user registers and clicks register the page hangs and freezes. Registration is successful but people think it didnt work and try to register again.
Errors in my logs are like this

Code Select Expand

[error] [client 185.24.xx.xx] PHP Warning:  Cannot modify header information - headers already sent by (output started at /home/hazardco/public_html/forum/Sources/Errors.php:415) in /home/hazardco/public_html/forum/Sources/Errors.php on line 353, referer: http://forum.hazardcourse.com/index.php?action=register2
[Wed Nov 30 22:30:02 2016] [error] [client 185.24.xx.xx] PHP Warning:  Cannot modify header information - headers already sent by (output started at /home/hazardco/public_html/forum/Sources/Errors.php:415) in /home/hazardco/public_html/forum/Sources/Errors.php on line 352, referer: http://forum.hazardcourse.com/index.php?action=register2
[Wed Nov 30 22:30:02 2016] [error] [client 185.24.xx.xx] PHP Warning:  Cannot modify header information - headers already sent by (output started at /home/hazardco/public_html/forum/Sources/Errors.php:415) in /home/hazardco/public_html/forum/Sources/Errors.php on line 351, referer: http://forum.hazardcourse.com/index.php?action=register2
[Wed Nov 30 22:30:02 2016] [error] [client 185.24.xx.xx] PHP Warning:  Cannot modify header information - headers already sent by (output started at /home/hazardco/public_html/forum/Sources/Errors.php:415) in /home/hazardco/public_html/forum/Sources/Errors.php on line 348, referer: http://forum.hazardcourse.com/index.php?action=register2
[Wed Nov 30 22:30:02 2016] [error] [client 185.24.xx.xx] PHP Warning:  Cannot modify header information - headers already sent by (output started at /home/hazardco/public_html/forum/Sources/Errors.php:415) in /home/hazardco/public_html/forum/Sources/Errors.php on line 347, referer: http://forum.hazardcourse.com/index.php?action=register2
[Wed Nov 30 22:30:02 2016] [error] [client 185.24.xx.xx] PHP Warning:  Cannot modify header information - headers already sent by (output started at /home/hazardco/public_html/forum/Sources/Errors.php:415) in /home/hazardco/public_html/forum/Sources/Errors.php on line 346, referer: http://forum.hazardcourse.com/index.php?action=register2

Also I get this on google chrome console when its frozen.

Failed to load resource: the server responded with a status of 500 (Internal Server Error) hxxp:forum.hazardcourse.com/index.php?action=register [nonactive]

[Kindred]

What mods do you have installed?

[Tridz]

What mods do you have installed?

I have social icons,@mention,oharayoutubeembed
My mailing system is also not working so I added questions to registering page to avoid bots and still allow users to register without email authentication.
I am thinking if this is the reason? Maybe when a user regsiters it also tries to send an email and since my configuration is wrong it goes timeout and the page hangs.
I cant fix mailing now I am waiting for my hosting provider to fix the issue.

Edit: If I wait long enough it gives me this error.

Connection Problems

Sorry, SMF was unable to connect to the database. This may be caused by the server being busy. Please try again later.

Forum is working fine.

[Tridz]

What mods do you have installed?

Ok I think problem is about emailing. I had smtp selected and the server cant establish smtp connection and just freezes. Now I have php selected on mailing. Registration is working fine but it is still not sending emails.

[ziycon]

Tridz, did you get this sorted, did you check your server logs to see if there are any errors relating to mails not sending? if there are no errors did you check your junk or spam mail folders?