Functions.php on Twentyten child theme causes blank pages (MU setup)

I tried something else recently. I took a TwentyTen theme, changed the name on it in the style.css file, and then made all my changes on my hard drive. I uploaded it as a new theme and activated it, but still got the white screen of death (even in the admin area).

Finally figured this out.

In my case, I was trying to resize the header. I was copying the complete functions file into the child theme and then changing the header size.

What worked in the end was copying ONLY the header image size code (not the entire file) into the child theme and changing it.

For example, the original height of the header was 198px, but I wanted to change it to 100px. So this is what my functions.php file looks like in my child theme (only this):

<?php

// The height and width of your custom header. You can hook into the theme's own filters to change these values.
	// Add a filter to twentyten_header_image_width and twentyten_header_image_height to change these values.
	define( 'HEADER_IMAGE_WIDTH', apply_filters( 'twentyten_header_image_width', 940 ) );
	define( 'HEADER_IMAGE_HEIGHT', apply_filters( 'twentyten_header_image_height', 100 ) );

?>

Important point you’ve made: only put into your child theme’s functions any additions or modifications to the parent theme’s functions; and in some cases, necessary to use the ‘remove_action’ to override the parent theme’s code. Read more in the codex about child themes and functions.php.

Glad you’ve worked it out. : )

Hi, I’ve been having the same problem as trivum – wanting to change the size of my header in Twentyten. I followed the steps above and created a functions.php file with the exact same code (but with my own header dimensions) and uploaded it to my child theme folder via ftp. I previewed the result in my browser and it looked perfect, but then when I went to log in to my WordPress admin I was blocked out by an error message saying that the functions were coming from the parent theme. When I deleted the new functions.php file from the child theme, I was allowed back in to my admin panel, but, of course, the header reverted back to the original default size. I can change the size in the parent functions.php file, and it works fine. But I would rather have a fully functioning child theme, as this would seem to be optimal best practice – any thoughts on this (I wish I could work it out too!)

Tim, what do you mean by “blocked out by an error message saying that the functions were coming from the parent theme”? Have you got WordPress debugging on? And by blocked out from your admin panel, do you mean the White Screen of Death? Because if this is the case, it’s possible that you accidentally left blank spaces or typos in your functions.php, or perhaps the code was wrongly constructed or placed incorrectly…

For changing header images and sizes, recommend this solution authored by David Cox over at Digital Raindrops.

Hi daitya, sorry for the delay in replying. The error that I am getting when trying to log in to the admin panel is this:

Warning: Cannot modify header information – headers already sent by (output started at /home/directory info in here/wp-content/themes/twentytenchild/functions.php:1) in /home/directory info in here/wp-includes/pluggable.php on line 897

It does appear on a white screen – not sure if that is TWOD.

Thanks for the tips on blanks and typos, I will check
the code – although it should be OK as I copied it directly from the parent theme (as demonstrated by trivum in the above example. Thanks also for the link to David Cox’s solution – I will explore that also.

@trivum!! that completely did the trick.

i think part of the problem is, when overriding a function (as opposed to inserting a new one) all it wants is the actual CHANGES, not the extra parts of the function code.

i’m no programmer, but i tried every possible configuration to change the header size, assuming that i needed to call the function to begin with… but as in @trivum’s solution, only the definitions were needed, not the function twentyten_setup() { bit.

i did not experience the lock out that @tim did… copied trivum’s code exactly.

Thanks for the fixes!

Dear All,

Thank you all for your suggestions. Finally after lots of reading and trials and helps from others, I was able to figure out and solve the problem.

Cheers
Mehmet