Warning: Cannot modify header information - headers already sent by (two headers on one page?)
41
How to fix "Headers already sent" error in PHP
43784
Workarounds for Sites page to update standard object?
78861
Why are there two separate boxes about duplicate questions?
74972
Redirecting depends of Variables in Header
119116
header location doesn't work and still in protect page
48580
postfix discard or change Message-ID header based on another header line
104745
Insert query on page load, inserts twice?
50644
Cannot post a duplicate message on chat even after the first message is edited, chat eats up the second message
34112
PHP: session variables are overwritten by declared variables with same name
135645
Replacement for drupal_add_http_header()
105400
What should we do about *identical* cross-site duplicates? (i.e., copy-and-paste cross-posting)
137666
Can I change the headers of the HTTP request sent by the browser?
122532
Header message just like at Stack Overflow
109875
Different headers for odd and even pages
25468
Is there a case where including the same header twice is actually helpful?
120619
What is "the URL" that restricts the Host header?
11295
What is duplicate content and how can I avoid being penalized for it on my site?