headers already sent error log regardless what I do

Hi @mobizma,
This happens when you have other page caching plugins present in your website which is also trying to modify the header information like this plugin. When using this plugin you need to make sure no other page caching plugins are present in your website. If you have some, just deactivate and delete them from Wp Admin > plugins section.

There is also a possibility that you might have some custom code in your theme where the theme is trying to modify the header information as a result the plugin can’t do it’s work.

To check what’s going on… you should first try disabling all plugins you have except this one to see if you are still getting this issue. If you are still seeing this header already sent, then temporarily switch to a default WP theme and check again. This will help you identify if this is happening from other plugins or your theme.

Hi Sauma!

[2] I use elementor Hello theme [super minimal plain vanilla] and the only plugin that would change headers would be the converter for media one.

[1] I no longer use any caching plugins since using yours and converter for media plugin.

[3] I did add custom code to htaccess for gzip. Aside from this maybe etag still left in the file from LS Cache. see below my code.

[4] the converter for media plugin adds an .htaccess to uploads folder with:

BEGIN Converter for Media

! — DO NOT EDIT PREVIOUS LINE — !

RewriteEngine On RewriteOptions Inherit RewriteCond %{HTTP_ACCEPT} image/avif RewriteCond %{REQUEST_FILENAME} -f RewriteCond %{DOCUMENT_ROOT}/wp-content/uploads-webpc/uploads/$1.jpg.avif -f RewriteRule (.+).jpg$ /wp-content/uploads-webpc/uploads/$1.jpg.avif [NC,T=image/avif,L] RewriteCond %{HTTP_ACCEPT} image/avif RewriteCond %{REQUEST_FILENAME} -f RewriteCond %{DOCUMENT_ROOT}/wp-content/uploads-webpc/uploads/$1.png.avif -f RewriteRule (.+).png$ /wp-content/uploads-webpc/uploads/$1.png.avif [NC,T=image/avif,L] RewriteCond %{HTTP_ACCEPT} image/avif RewriteCond %{REQUEST_FILENAME} -f RewriteCond %{DOCUMENT_ROOT}/wp-content/uploads-webpc/uploads/$1.gif.avif -f RewriteRule (.+).gif$ /wp-content/uploads-webpc/uploads/$1.gif.avif [NC,T=image/avif,L] RewriteCond %{HTTP_ACCEPT} image/avif RewriteCond %{REQUEST_FILENAME} -f RewriteCond %{DOCUMENT_ROOT}/wp-content/uploads-webpc/uploads/$1.webp.avif -f RewriteRule (.+).webp$ /wp-content/uploads-webpc/uploads/$1.webp.avif [NC,T=image/avif,L] RewriteCond %{HTTP_ACCEPT} image/avif RewriteCond %{REQUEST_FILENAME} -f RewriteCond %{DOCUMENT_ROOT}/wp-content/uploads-webpc/uploads/$1.jpeg.avif -f RewriteRule (.+).jpeg$ /wp-content/uploads-webpc/uploads/$1.jpeg.avif [NC,T=image/avif,L]
RewriteEngine On RewriteOptions Inherit RewriteCond %{HTTP_ACCEPT} image/webp RewriteCond %{REQUEST_FILENAME} -f RewriteCond %{DOCUMENT_ROOT}/wp-content/uploads-webpc/uploads/$1.jpg.webp -f RewriteRule (.+).jpg$ /wp-content/uploads-webpc/uploads/$1.jpg.webp [NC,T=image/webp,L] RewriteCond %{HTTP_ACCEPT} image/webp RewriteCond %{REQUEST_FILENAME} -f RewriteCond %{DOCUMENT_ROOT}/wp-content/uploads-webpc/uploads/$1.png.webp -f RewriteRule (.+).png$ /wp-content/uploads-webpc/uploads/$1.png.webp [NC,T=image/webp,L] RewriteCond %{HTTP_ACCEPT} image/webp RewriteCond %{REQUEST_FILENAME} -f RewriteCond %{DOCUMENT_ROOT}/wp-content/uploads-webpc/uploads/$1.gif.webp -f RewriteRule (.+).gif$ /wp-content/uploads-webpc/uploads/$1.gif.webp [NC,T=image/webp,L] RewriteCond %{HTTP_ACCEPT} image/webp RewriteCond %{REQUEST_FILENAME} -f RewriteCond %{DOCUMENT_ROOT}/wp-content/uploads-webpc/uploads/$1.webp.webp -f RewriteRule (.+).webp$ /wp-content/uploads-webpc/uploads/$1.webp.webp [NC,T=image/webp,L] RewriteCond %{HTTP_ACCEPT} image/webp RewriteCond %{REQUEST_FILENAME} -f RewriteCond %{DOCUMENT_ROOT}/wp-content/uploads-webpc/uploads/$1.jpeg.webp -f RewriteRule (.+).jpeg$ /wp-content/uploads-webpc/uploads/$1.jpeg.webp [NC,T=image/webp,L]

! — DO NOT EDIT NEXT LINE — !

END Converter for Media

and it adds in wp-content/ .htaccess:

BEGIN Converter for Media

! — DO NOT EDIT PREVIOUS LINE — !

RewriteEngine On RewriteOptions Inherit RewriteCond %{HTTP_ACCEPT} image/avif RewriteCond %{REQUEST_FILENAME} -f RewriteCond %{DOCUMENT_ROOT}/wp-content/uploads-webpc/$1.jpg.avif -f RewriteRule (.+).jpg$ /wp-content/uploads-webpc/$1.jpg.avif [NC,T=image/avif,L] RewriteCond %{HTTP_ACCEPT} image/avif RewriteCond %{REQUEST_FILENAME} -f RewriteCond %{DOCUMENT_ROOT}/wp-content/uploads-webpc/$1.png.avif -f RewriteRule (.+).png$ /wp-content/uploads-webpc/$1.png.avif [NC,T=image/avif,L] RewriteCond %{HTTP_ACCEPT} image/avif RewriteCond %{REQUEST_FILENAME} -f RewriteCond %{DOCUMENT_ROOT}/wp-content/uploads-webpc/$1.gif.avif -f RewriteRule (.+).gif$ /wp-content/uploads-webpc/$1.gif.avif [NC,T=image/avif,L] RewriteCond %{HTTP_ACCEPT} image/avif RewriteCond %{REQUEST_FILENAME} -f RewriteCond %{DOCUMENT_ROOT}/wp-content/uploads-webpc/$1.webp.avif -f RewriteRule (.+).webp$ /wp-content/uploads-webpc/$1.webp.avif [NC,T=image/avif,L] RewriteCond %{HTTP_ACCEPT} image/avif RewriteCond %{REQUEST_FILENAME} -f RewriteCond %{DOCUMENT_ROOT}/wp-content/uploads-webpc/$1.jpeg.avif -f RewriteRule (.+).jpeg$ /wp-content/uploads-webpc/$1.jpeg.avif [NC,T=image/avif,L]
RewriteEngine On RewriteOptions Inherit RewriteCond %{HTTP_ACCEPT} image/webp RewriteCond %{REQUEST_FILENAME} -f RewriteCond %{DOCUMENT_ROOT}/wp-content/uploads-webpc/$1.jpg.webp -f RewriteRule (.+).jpg$ /wp-content/uploads-webpc/$1.jpg.webp [NC,T=image/webp,L] RewriteCond %{HTTP_ACCEPT} image/webp RewriteCond %{REQUEST_FILENAME} -f RewriteCond %{DOCUMENT_ROOT}/wp-content/uploads-webpc/$1.png.webp -f RewriteRule (.+).png$ /wp-content/uploads-webpc/$1.png.webp [NC,T=image/webp,L] RewriteCond %{HTTP_ACCEPT} image/webp RewriteCond %{REQUEST_FILENAME} -f RewriteCond %{DOCUMENT_ROOT}/wp-content/uploads-webpc/$1.gif.webp -f RewriteRule (.+).gif$ /wp-content/uploads-webpc/$1.gif.webp [NC,T=image/webp,L] RewriteCond %{HTTP_ACCEPT} image/webp RewriteCond %{REQUEST_FILENAME} -f RewriteCond %{DOCUMENT_ROOT}/wp-content/uploads-webpc/$1.webp.webp -f RewriteRule (.+).webp$ /wp-content/uploads-webpc/$1.webp.webp [NC,T=image/webp,L] RewriteCond %{HTTP_ACCEPT} image/webp RewriteCond %{REQUEST_FILENAME} -f RewriteCond %{DOCUMENT_ROOT}/wp-content/uploads-webpc/$1.jpeg.webp -f RewriteRule (.+).jpeg$ /wp-content/uploads-webpc/$1.jpeg.webp [NC,T=image/webp,L]
Header always set Cache-Control “private” Header append Vary “Accept”

! — DO NOT EDIT NEXT LINE — !

END Converter for Media

I have security hardening codes, the WP section and then this in my ROOT .htaccess:

# Compress HTML, CSS, JavaScript, Text, XML and fonts
AddOutputFilterByType DEFLATE application/javascript
AddOutputFilterByType DEFLATE application/rss+xml
AddOutputFilterByType DEFLATE application/vnd.ms-fontobject
AddOutputFilterByType DEFLATE application/x-font
AddOutputFilterByType DEFLATE application/x-font-opentype
AddOutputFilterByType DEFLATE application/x-font-otf
AddOutputFilterByType DEFLATE application/x-font-truetype
AddOutputFilterByType DEFLATE application/x-font-ttf
AddOutputFilterByType DEFLATE application/x-javascript
AddOutputFilterByType DEFLATE application/xhtml+xml
AddOutputFilterByType DEFLATE application/xml
AddOutputFilterByType DEFLATE font/opentype
AddOutputFilterByType DEFLATE font/otf
AddOutputFilterByType DEFLATE font/ttf
AddOutputFilterByType DEFLATE image/svg+xml
AddOutputFilterByType DEFLATE image/x-icon
AddOutputFilterByType DEFLATE text/css
AddOutputFilterByType DEFLATE text/html
AddOutputFilterByType DEFLATE text/javascript
AddOutputFilterByType DEFLATE text/plain
AddOutputFilterByType DEFLATE text/xml

# Remove browser bugs (only needed for really old browsers)
BrowserMatch ^Mozilla/4 gzip-only-text/html
BrowserMatch ^Mozilla/4.0[678] no-gzip
BrowserMatch \bMSIE !no-gzip !gzip-only-text/html
Header append Vary User-Agent


BEGIN LiteSpeed

The directives (lines) between "BEGIN LiteSpeed" and "END LiteSpeed" are

dynamically generated, and should only be modified via WordPress filters.

Any changes to the directives between these markers will be overwritten.

SetEnv noabort 1

END LiteSpeed

BEGIN WP Cloudflare Super Page Cache

The directives (lines) between "BEGIN WP Cloudflare Super Page Cache" and "END WP Cloudflare Super Page Cache" are

dynamically generated, and should only be modified via WordPress filters.

Any changes to the directives between these markers will be overwritten.

ExpiresActive on ExpiresByType application/xml "access plus 0 seconds" ExpiresByType text/xsl "access plus 0 seconds"
Header set Cache-Control "no-cache, no-store, must-revalidate, max-age=0"
Header set Cache-Control "no-cache, no-store, must-revalidate, max-age=0"
Header set Cache-Control "public, must-revalidate, proxy-revalidate, immutable, max-age=2592000, stale-while-revalidate=86400, stale-if-error=604800"
Header set Cache-Control "public, must-revalidate, proxy-revalidate, immutable, max-age=31536000, stale-while-revalidate=86400, stale-if-error=604800"
RewriteCond %{REQUEST_URI} ^(.)?/wp-content/wp-cloudflare-super-page-cache/sonohz.com/debug.log(.)$ RewriteRule ^(.*)$ - [F]
Header set Cache-Control "no-cache, no-store, must-revalidate, max-age=0"

END WP Cloudflare Super Page Cache

Hi @mobizma,
Can you momentarily remove all the htaccess rules except the ones added by WP core and this plugin and then check if the issue gets resolved or not.

If I remove the other htaccess I suspect it’d basically destroy the converter for media plugin interaction with CloudFlare or functionality. And I don’t wish to disable or stop using that plugin.

We simply need yours to play with it without conflict.

The other root .htaccess rules are simply ones I have in all my many websites to harden security, like file access to debug, hitting on author URLs etc. nothing to do with headers. Those other sites have zero such debug log warnings. I don’t have your plugin on them not converter for media.

I don’t use many security plugins and add custom code in a custom functions file, but that’s not for altering headers. And deactivating the file is not changing anything. I have security and bloat related functions, like:

/** hide wp version – Remove meta generator **/
// remove version from head
remove_action(‘wp_head’, ‘wp_generator’);

// remove version from rss
add_filter(‘the_generator’, ‘__return_empty_string’);

Plus some other custom functions to disable self-pingbacks, emojis, hide author login, disable embeds & oEmbed discovery, remove wlwmanifest link, version mentions, disable XML/RPC etc.

Hence my intuitive logic makes me think since yours and CFM both try to set headers and since you have even a setting to play along with other plugins, perhaps it needs expanding to resolve this issue.

But I am not a coder, so may get it all wrong.

Hi @mobizma,

those functions are not doing anything. I’m not asking you to delete those htacess rule for good. I’m asking you delete them for testing, you can save them in a notepad so that you can add them once the test is done.

Basically you need to look what else is modifying header. From my experience it is a plugin. That’s why I suggested you to test with all your other plugin disabled and then of the issue is not solved try a default theme. But my hunch is it’s a plugin.

Correct and I assume it is the image optimization plugin which simply needs yours to support it. Or communicate with their author perhaps to be supported. Nothing else I can think about is causing this.

Hi @mobizma,
First you need to test and confirm if it’s the image optimization plugin or not. There is no way to support it if they are also manipulating headers. As when using this plugin, other plugins are not supposed to manipulate the headers.

If you can confirm that it is this plugin which is causing the issue, I would suggest you to opt for a different image optimization system like Optimole, Imagekit.io or maybe Cloudflare Pro plan.