i want exclude debug infomation when output csv

In fact, CI4 does not support stream output except in case of downloading an existing file.
See https://codeigniter4.github.io/CodeIgnit...e-download

Even if you want to output stream in your controller, all output will be buffered and sent by the framework.

If you need to disable the output buffering, put the following code before your stream output.

PHP Code:

while (ob_get_level() > 0) {
    ob_end_clean();
} 


ci-phpunit-test | CodeIgniter Testing Guide | CodeIgniter 3 to 4 Upgrade Helper