MYSQL_ATTR_INIT_COMMAND causing "The FastCGI process exited unexpectedly"

Description

We have some PHP code that has ran fine for years under PHP 7 / IIS / FastCGI

When updating to PHP 8.1.9 we're getting "The FastCGI process exited unexpectedly"

After digging through the code we have identified the issue as follows:

When using PDO::MYSQL_ATTR_INIT_COMMAND in the new PDO() constructor - FastCGI just dies

		$options = [
			PDO::ATTR_ERRMODE            => PDO::ERRMODE_EXCEPTION,
			PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
			PDO::ATTR_EMULATE_PREPARES   => false,
			PDO::MYSQL_ATTR_INIT_COMMAND => "SET NAMES utf8mb4;"
		];

            $this->m_db = new PDO(
                $m_PDOConnectionString,
                $Username,
                $Password,
                $options
            );

Resulted in this output:

C:\Program Files (x86)\PHP\v8.1.9.dev\php-cgi.exe - The FastCGI process exited unexpectedly

But I expected this output instead:

N/A - expected DB connection to open as normal

Only thing i can find in the windows event log is as follows:

Faulting application name: php-cgi.exe, version: 8.1.9.0, time stamp: 0x62e93213
Faulting module name: php8.dll, version: 8.1.9.0, time stamp: 0x62e93aac
Exception code: 0xc0000005
Fault offset: 0x00008fac
Faulting process id: 0x4d4
Faulting application start time: 0x01d8b3db35c39991
Faulting application path: C:\Program Files (x86)\PHP\v8.1.9.dev\php-cgi.exe
Faulting module path: C:\Program Files (x86)\PHP\v8.1.9.dev\php8.dll
Report Id: 3737167c-6b9f-48b2-bdfb-74baff4570ec
Faulting package full name: 
Faulting package-relative application ID: 

Removing MYSQL_ATTR_INIT_COMMAND solves the prooblem and everything starts working again.

The systax we're using here, i.e. "SET NAMES utf8mb4;" is a valid MySQL command which we've tested in mySQL workbench etc

Is this related to https://github.com/php/php-src/issues/9143 i wonder?

PHP Version

8.1.9

Operating System

Windows Server 2019

Reproduce el fallo informado en PHP 8.1.9 sobre Windows Server 2019 con PDO::MYSQL_ATTR_INIT_COMMAND establecido en "SET NAMES utf8mb4;", y compáralo después con el mismo constructor sin esa opción. Empieza revisando el issue relacionado 9143 y los detalles proporcionados del registro de eventos de Windows; el trabajo estará terminado cuando el proceso FastCGI ya no finalice inesperadamente y la regresión esté cubierta por una prueba adecuada.