Error "Warning: cannot modify header...."

[overflo]

I have a dynamic website written on a comp running PHP 5 (and had also run on testing server running the same). I have uploaded to server which is running PHP 4.4.1.
The problem is I have some scripts that redirect after deleting and everything was running fine until I uploaded to server. Now I keep getting the error "Warning: Cannot modify header information - headers already sent by (output started at /home/landcare/public_html/functions_main.php:54) in /home/landcare/public_html/functions_delete.php on line 123
"
I have checked for whitespace before and after the php tags but there is none. Any suggestions would be greatly appreciated.

 

[BabyJeffy]

Look in functions_main.php at around line 54. The error suggests to me that you are indeed outputting something to the page (maybe an echo?) before you are attempting to send a header. Check you have no whitespace before the initial opening <? on your page that is erroring (and any includes you have on that page).

Cheers,
Jeff

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[overflo]

There is definitely no whitespace. It works fine on my computer and on testing server both running php5 but not on server running 4.4.1. Could this be the problem ?

 

[Vragabond]

Your functions_main could be calling a php5 specific function which would output an error in the previous versions. Outputed error would count as an output.

 

[overflo]

hmmm bummer coz theres a quite a few functions. Thanks for your help, I better get on it coz it's s'posed to be all up and running in 4 hours time

 

[overflo]

It's allowing the header("Location: $url") redirect when I'm adding to the database, but it comes up with the error only when I'm deleting.

 

[skiflyer]

So step through your debug process, and find out what might output an error or warning or some type of echo statement.

I'll give you a hint, it's on line 54 of functions_main.php

 

[overflo]

No. solved it. it just needed
ob_start();
I'd somehow overlooked it.

Thanks for all the replies.

 

[skiflyer]

ob_start() just buffers all the output... it doesn't mean you're not throwing any errors or warnings.

It's certainly one way to it, but it may be masking a bigger issue.