Upgrading a Cake 1.2 site

I posted this on Stack Overflow, but starting to lose hope of any more real help coming from there, and somehow managed not to notice this place earlier, so… reposting that one mostly verbatim here. Any help or hints much appreciated.

I’ve got a CakePHP 1.2-based web site (I know… too ancient) that I need to upgrade only to whatever is the oldest Cake to support PHP 7.1 (I think roughly 2.8?), because my host is upgrading PHP to 7.1 across the board. This site only needs to live maybe 1 more year before we totally replace it, but we don’t have time to do that before the host upgrades PHP at end of year.

I am trying to get the web site as-is running in a vagrant VM, so I can go through the upgrade steps there, carefully, and understand exactly what I need to do. My problem now is that I can’t get the site to display. More concretely, when I try to load the site with nginx in vagrant, I get nothing but a blank screen with a few PHP warnings (strict standards to the effect of Non-static method Configure::read() should not be called statically), but nothing obviously broken. There’s basically nothing in the PHP log, and nothing in the Nginx log. Again, this is the site as currently running (successfully) in production, which means my vagrant PHP is 5.6.38 (the actual production PHP is 5.6.25). Running with php-fpm.

Cake’s own logs are only reporting the following, which arises inside a controller method disableCache(), which is trying to insert headers to prevent the browser from caching the request:

2018-10-22 15:18:57 Warning: Warning (2): Cannot modify header information - headers already sent by (output started at /usr/share/nginx/html/www.mydomain.com/cake/libs/object.php:63) in [CORE/cake/libs/controller/controller.php, line 844]

I have inserted an early return in that method just to stop these warnings.

In PHP, I’ve got these settings:

ini_set('display_errors', 1);
ini_set('error_log', '/var/log/php_errors.log');

In Cake 1.2’s app/config/core.php, I’ve got:

Configure::write('debug', 3);

Database is local MySQL in vagrant, with settings in app/config/database.yml.

Can someone suggest where I should go next in debugging this?

Can you maybe past what is at line 63 of the /cake/libs/object.php file? That might give a clue what the issue is.

Unfortunately, Cake 1.2 is not available in our source control!

Thx… I don’t think it’ll be much help. Those warnings don’t seem to be related to the ultimate problem of the site not displaying. But line 63 is just the following function def:

* Class constructor, overridden in descendant classes.
function __construct() {