Error when loading magento after inserting $_SERVER['MAGE_PROFILER'] to index.php

[Eddcapone]

Preconditions

1. Magento 2.4.1

Steps to reproduce

1. Follow installation instructions

If you add $_SERVER['MAGE_PROFILER'] = [ 'drivers' => [['output' => 'MSP\DevTools\Profiler\Driver\Standard\Output\DevTools']] ]; to your index.php and pub/index.php, then you will get this error:

Warning: strlen() expects parameter 1 to be string, array given in /home/companyde/redesign.company.de/app/bootstrap.php on line 58

Warning: file_get_contents(/home/companyde/redesign.company.de/var/profiler.flag): failed to open stream: No such file or directory in /home/companyde/redesign.company.de/app/bootstrap.php on line 60
1 exception(s): Exception #0 (Exception): Warning: Cannot modify header information - headers already sent by (output started at /home/companyde/redesign.company.de/app/bootstrap.php:58) in /home/companyde/redesign.company.de/vendor/magento/framework/Stdlib/Cookie/PhpCookieManager.php on line 152 Exception #0 (Exception): Warning: Cannot modify header information - headers already sent by (output started at /home/companyde/redesign.company.de/app/bootstrap.php:58) in /home/companyde/redesign.company.de/vendor/magento/framework/Stdlib/Cookie/PhpCookieManager.php on line 152

Expected result

Actual result

1. [Screenshot, logs]

[mikeastral]

I just face the same problem when using Magento 2.4.x and Magento 2.3.7

I realized that a quick workaround, no matter what Magento version is being used, is to edit app/bootstrap.php instead on index.php and/or pub/index.php

Original

$profilerConfig = isset($_SERVER['MAGE_PROFILER']) && strlen($_SERVER['MAGE_PROFILER'])
    ? $_SERVER['MAGE_PROFILER']
    : trim(file_get_contents(BP . '/var/profiler.flag'));

if ($profilerConfig) {
    $profilerConfig = json_decode($profilerConfig, true) ?: $profilerConfig;
}

After modification:

$profilerConfig = $_SERVER['MAGE_PROFILER'] = [ 'drivers' => [['output' => 'MSP\DevTools\Profiler\Driver\Standard\Output\DevTools']] ];

/*$profilerConfig = isset($_SERVER['MAGE_PROFILER']) && strlen($_SERVER['MAGE_PROFILER'])
    ? $_SERVER['MAGE_PROFILER']
    : trim(file_get_contents(BP . '/var/profiler.flag'));

if ($profilerConfig) {
    $profilerConfig = json_decode($profilerConfig, true) ?: $profilerConfig;
}*/

[RobertoZeppilli]

Hi Mike, so I did the same thing, I moved the $_SERVER to app/bootstrap.php and save it in a variable as you did. But is not working. I flushed the cache, disabled Full Page Cache, upgraded the db and, enabled devtools and IP (I've added my IP) restrictions on admin page. But still is not working.