Cannot modify header only when using Bootstrap

Question

Alright, I was not able to find a problem like mine anywhere else, so here it is.

I am using a login function to login a user. After they put their data in, I send it through the function. This then returns values based on the result, which is used by a switch to display results to the user. If they get logged in, a cookie is set in the function. The switch then uses header('Location: /') to redirect the user.

The problem with this is that when I try using Bootstrap, it throws this error:

Warning: Cannot modify header information - headers already sent by
(output started at C:\wamp\www\assets\php\header.php:89) in
C:\wamp\www\assets\classes\Shortener.php on line 163

header.php; line 89: <br/><br/><br/> (this is the end of the file)

Shortener.php (login function); line 163:

setcookie('session', $db_session_hash, time()+3600, "/");

If I remove the bootstrap parts of this, it works absolutely fine! (which angers me the most)

header.php: https://pastebin.com/jnGtHSUy

Shortener.php (login function only): https://pastebin.com/i6CG54hw

I hope this is enough information. I've been angry at this ever since I've been getting this error.

No point in being angry. The error indicates that somewhere in the code, some text or HTML code was set to the output stream, at which point the header is "locked". Try commenting out line 89. That is putting stuff in the stream, so when Shortener is called, output has already been written — Sparky, Jun 28 '15 at 20:31
@Sparky I tried commenting it out, and then removing it. The error changed to line 88. It has to do something with the very last line. I have no idea why though. — , Jun 28 '15 at 20:35
Based on your code, comment out the ECHO commands in the PHP section. The minute not header HTML (such as your
possible duplicate of [How to fix "Headers already sent" error in PHP](http://stackoverflow.com/q/8028957) - You can *either* output HTML, *or* use a redirection header. Not both. Use one of the workarounds, or fix your processing logic. — mario, Jun 28 '15 at 20:37
@Sparky I also did that. In fact, I removed the entire nav there and now the error was on the login page on a line that had the opening PHP tags on it. — , Jun 28 '15 at 20:41
I just now removed everywhere a bootstrap item was called. Ex: `col-lg-4`, and everything is working perfectly. It is something to do with Bootstrap. — , Jun 28 '15 at 20:45

Ben T · Accepted Answer · 2015-06-28T21:02:07.973

1

Somehow your login function is being called partway through the page, instead of before the header file is included. There are 2 ways to solve this, Zak:

Set the cookie first (by making sure that login() is always called before the template data), before you include any HTML. Shortly after you begin to output the page content (header content in this case), the server will output the HTTP headers (where the cookie should be), and then the HTML content. As soon as the server sends the headers, you can no longer set cookies.
You can increase the output buffering as set in your php.ini file. I think I have mine set at 4096, but higher values mean more HTML content before the headers are sent. This is why the Bootstrap lines are the difference between overrunning the output buffer before you set your cookie or not overrunning the buffer's space. Now, this is a lousy solution albeit a handy piece of knowledge.

edited Jun 28 '15 at 21:02

answered Jun 28 '15 at 20:55

Ben T

202
1
4

YES! Okay what I did was I moved the login class being called and the part where the login function was called on the very top of the login page, in an `if` statement of course, which is called when a `post` request is sent. After this, I called the header.php page. Then I put the html stuff (the form, etc.). After that I added the switch statement that is called if the login variable is set... (awful explanation, but it works!) Thank you!!! tl;dr: https://pastebin.com/ePRkmVR6 – Jun 28 '15 at 21:08
Exactly, @Zak! Glad I was able to help you. Feel free to mark my answer as correct, and upvote it. Have a great day! – Ben T Jun 28 '15 at 21:10

score 0 · Answer 2 · edited Jan 27 '19 at 07:14

0

You need to set a larger output buffer in your php.ini or set it by .htaccess:

output_buffering = 12288

The default of 4096 may fall short once you add larger scripts and css sections.

edited Jan 27 '19 at 07:14

Sanne

1,116
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answered Jan 26 '19 at 23:46

marrtins

1

Cannot modify header only when using Bootstrap

If I remove the bootstrap parts of this, it works absolutely fine! (which angers me the most)

2 Answers2