Since the ISAPI modules changed their names, from php4xxx to php5xxx, you need to make some changes in the configuration files. There were also changes in the CLI and CGI filenames. Please refer to the corresponding section for more information.
Migrate the Apache configuration is extremely easy. See the example below to check the change you need to do:
If your webserver is running PHP in CGI mode, you should note that the CGI version has changed its name from php.exe to php-cgi.exe. In Apache you should do something like this:
In other webservers you need to change either the CGI or the ISAPI module filenames.