I've upgraded PHP from 4.1.2 to 4.2.1 and all variables passed via url parameters are empty.
For example:

http://mysite.com/detail.php?order=1&sid=15

inside detail.php $order and $sid are not set.

I have to modify all the pages to include things like:

$sid=$HTTP_GET_VARS['sid'];

and then sid get the desired value (15).

I've compiled this version exactly the same way as 4.1.2 and in the older version it works ok (under SuSE 8).

Files & versions:
----------------
 apache_1.3.24.tar.gz
 c-client.tar.Z
 mod_ssl-2.8.8-1.3.24.tar.gz
 openssl-0.9.6c.tar.gz
 php-4.2.1.tar.gz   and  php-4.1.2.tar.gz

-----------------------------------------------------------
The following is the script I used to compile:

# Instalaci?n de apache (1ra. parte)
# ----------------------------------
tar zxf apache_1.3.24.tar.gz
cd apache_1.3.24
./configure --prefix=/webmail
cd ..

# Instalaci?n de OpenSSL
# ----------------------

tar zxf openssl-0.9.6c.tar.gz
cd openssl-0.9.6c
./config
make
make test
make install
cd ..

# Instalaci?n de Mod_SSL sin certificado
# --------------------------------------

tar zxf mod_ssl-2.8.8-1.3.24.tar.gz 
cd mod_ssl-2.8.8-1.3.24
./configure \
    --with-apache=../apache_1.3.24 \
    --with-ssl=../openssl-0.9.6c \
    --prefix=/webmail
cd ..

# Librer?a c-client para IMAP
# ---------------------------

tar zxf c-client.tar.Z
cd imap-2001.BETA.SNAP-0107221451/
make slx

cp c-client/c-client.a /usr/local/lib/c-client.a
cp c-client/rfc822.h /usr/local/include 
cp c-client/mail.h /usr/local/include
cp c-client/linkage.h /usr/local/include
cd ..


# Instalaci?n de php4
# -------------------

tar zxf php-4.2.1.tar.gz
cd php-4.2.1
./configure --with-mysql --with-apache=../apache_1.3.24 --enable-track-vars --with-imap --with-oci8
make
make install
cp php.ini-dist /usr/local/lib/php.ini
cd ..

cd apache_1.3.24
./configure --prefix=/webmail --activate-module=src/modules/php4/libphp4.a --enable-module=ssl
make
make certificate TYPE=custom
	
make install

----------------------
And then in httpd.conf:
DirectoryIndex index.html index.php index.php3

AddType application/x-httpd-php .php
AddType application/x-httpd-php-source .phps
AddType application/x-httpd-php .php3