headers already sent by qa-xml-sitemap.php:293

[q2apro]

Hi everyone, I am getting the following error once in a while (which fills my error_log):

PHP Warning:  Cannot modify header information - headers already sent by (output started at /qa-plugin/xml-sitemap/qa-xml-sitemap.php:293) in qa-include/qa-app-users.php on line 1042

Line 293 from qa-xml-sitemap.php is:

"\t</url>\n";

What could be the problem and how can I fix this?

Thanks
Kai

PS: I know this is a plugin issue but I am posting this error here because this plugin comes only with the core distribution.

[svivian]

I cannot reproduce this error here. Is there perhaps another plugin that's causing it? Can you try temporarily removing any non-official plugins and see if the error still occurs? If so, try putting them back one at a time until you find the plugin causing the error.

[svivian]

@q2apro Any luck reproducing the issue? Does it occur when you load the sitemap yourself (e.g. your-q2a-site.com/sitemap.xml)

[q2apro]

I realized that loading the your-q2a-site.com/sitemap.xml created the error. Getting this error means for me a bot crawled the sitemap URL.

I disabled each plugin one by one, loaded the sitemap.xml, and tried to find out if the error does not appear. The error appeared no matter what plugin I disabled. Still have no clue. I will update with v1.7 to see if the problem goes away. Just wait for the release :)

[svivian]

OK I found the issue! It occurs only when logged out. Strangely, it also only occurs when I include the user accounts in the sitemap, though I think that may be related to output buffering.

In qa_get_request_content the content is fetched, then qa_set_form_security_key is called which sets a cookie for non logged-in users. However in the case of the sitemap plugin, instead of returning $qa_content it outputs content immediately which prevents the cookie setting.

Anyway, it looks like this particular problem can be fixed by only calling the function if qa_content exists (qa-page.php line 227):

if (isset($qa_content))
    qa_set_form_security_key();

[q2apro]

Great work! In my installation I unchecked the "Include user pages" for the xml sitemap plugin now. Let's see if this fixes the error. Or if I need to change the code as you suggested.

[svivian]

I don't think it's specifically the user pages, I think it's the size of the sitemap output. I only have a few questions on my test site but many users. If you have many questions you will probably get the same error without the users.

[q2apro]

All right, I added the line in qa-page.php. Seems to be fixed now. When calling the stemap.xml (logged-in or logged-out) the error does not appear anymore.