header information – headers already sent by…??

…I want to add that it also happens with a standard theme (Twenty Fifteen) and all plugins deactivated. It’s a more or less new installation.
Thanks

This often is caused by a theme or a function.php or a mu_plugin file that outputs blank lines or other unnecessary output, some times as simple as a blank line at the end of functions.php that forces early output and results in this problem. Its a fairly common wordpress error.

Its a matter of finding out where it is.

I would first try removing any mu-plugins or custom functions.php. If that fixes it then inspect these more closely (especially for blank lines at end of the file).

Failing that I would try it in a clean installation of wordpress and wtf-fu with nothing else then reinstall things one at a time to see where the problem lies.

Let me know how you get on,

Lynton

I take it back I just tried a fresh install using the new wordpress 4.3 and I can see this exact behavior you describe.

Something has changed in 4.3,

No need for you to do anything now, please just wait for me to investigate further.

thanks for alerting me to this.

stay tuned …

I tried updating another install to 4.3 and all was fine, however after playing with the new 4.3 theme customizer I again starting seeing these issues.

Everything seems to work as expected though except for these ugly messages on the top of the screen.

Are you using 4.3 and have you used the theme customer ?
Is it the same for you, in that it still works just messy ?

thanks
lynton

I’m using WP 4.2.4 (and I still haven’t updated to 4.3).
If I used the ‘theme customizer’? I don’t know what it is (are you talking about: Menu Customizer – Manage your Menus in the Customizer. WordPress core feature-plugin merged in WordPress 4.3.??
NO. I never used it (think so).

But it seems that we are not the only one:
https://www.ads-software.com/support/topic/warnings-using-theme-customizer-with-wordpress-43?replies=3

Ah thanks I went from 4.2.3 to 4.3. So it looks like something changed worth the way themes work in 4.2.4

This may take some time to figure out. But I will keep looking.

I am not too worried as everything still appears to work, even though it looks bad.

Let me know if this is stopping anything for you.

I installed the plugin on WordPress 4.2.1 and I get the following message:

The plugin generated 474 characters of unexpected output during activation. If you notice “headers already sent” messages, problems with syndication feeds or other issues, try deactivating or removing this plugin.

The problem I described at the beginning of these posts are on 4.2.4 and you have the problem on 4.3.

Sorry but please could you investigate further your plugin?

I have found and corrected the warnings,

I also tested installing 3.0.0 into WP 4.2.1 and saw the warning. I tested some others version that I had around and did not find this anywhere else.

I will release the warnings fixes in the near future. I believe this is harmless though and it should not cause any real problems other than displaying the warnings on the workflow and templates admin screens.

The issue with installation into WP 4.2.1 I don’t intend to look at as it only happens in that WP version and is only a one off warning during installation.

regards

Lynton.