Blank page on the web server

Try putting the forced error at the end of the page - it will make a difference to the generated errors and they may be more understandable.

Code:

<?php echo $bad_value/$bad; ?>
</body>
</html>

Also examine the script just before the second critical error and see what was written that caused there error:

Code:

CRITICAL - 2020-04-22 13:29:01 --> Uncaught ErrorException: Cannot modify header information - headers already sent by (output started at /home/xxinsp/ci4/app/Config/Events.php:27) in /home/xxinsp/ci4/system/Debug/Exceptions.php:161
Stack trace:
#0 [internal function]: CodeIgniter\Debug\Exceptions->errorHandler(2, 'Cannot modify h...', '/home/xxinsp/ci...', 161, Array)
#1 /home/xxinsp/ci4/system/Debug/Exceptions.php(161): header('HTTP/1.1 500 In...', true, 500)
#2 [internal function]: CodeIgniter\Debug\Exceptions->exceptionHandler(Object(ErrorException))

Tentatively Tapped on a Tabket