Underscore character in header keys is not allowed on some load balancers

[humbertocastelo]

Hello, today I identified the presence of the underscore/underline character (_) in the header keys and this is prohibited in several stricter load balancers / reverse proxies, for example, Oracle's Load Balancer returns the error "Backend x.x.x.x returned invalid header"

Files:

1 - output/Headers.php

1.1 - header( sprintf( 'X-QM-%s-%s: %s', $id, $key, $value ) ); // replace from _ to - in $id and $key

2 - assets/query-monitor.js

2.1 - X-QM-php_errors-error-count > X-QM-php-errors-error-count
2.2 - X-QM-php_errors-error- > X-QM-php-errors-error-

[johnbillion]

Computers are fun!