Blank page after move to Phalcon 4 php 7.4

[alfeltrin]

I have move an old application from a server with phalcon 3 and php 5 to another with phalcon 4 and php 7.4.
After that i get a blank screen and i don't know how to display the Phalcon errors.
I've check if phalcon is working and all wark fine with a simple 'Hello world'
But when i try to use Models, something goes wrong and i got a blank page instead of an error...there's a way to display the error message?

[quasipickle]

By default PHP is configured to hide errors. Moving from 3 to 4, you almost certainly have fatal errors in your application - they're just not getting displayed.

Proper production environments should never display PHP errors. However, if this is just internal or a development server showing the errors on the screen should be fine.

Find the php.ini file that is being used (phpinfo() on a page - not command line - will tell you that), then look for the display_errors directive and set it to "on". Then, restart Apache & you should see a bunch of stuff on the screen telling you what to fix.

You should also read the upgrade guide: https://docs.phalcon.io/4.0/en/upgrade.

[alfeltrin]

I have enabled the display of errors inside index.php
error_reporting("E_ALL"); ini_set('display_errors', 1); ini_set('display_startup_errors', 1);
However only some errors are displayed (it shows if it can't find a controller or an action inside the controller), but if the error occurre inside the controller code it shows a blank page

[quasipickle]

Changing the ini settings in-code requires the code to be fully parseable. If there's a fatal error that happens during parsing or before your ini_set() calls get run, you won't see those errors

Changing the setting in php.ini will cause error reporting to be enabled before your code gets parsed, so those errors will be caught & displayed.

[zikezhang]

there are a variety of reasons cause the blank page.

1. Please check your web server log.
2. check Phalcon 4 response :

if (!$response->isSent()) { $response->send(); }