How to convert Pdf file to byte array in php and send?

I have found pdf to byte array and vice-versa in java,dotnet and python. But i want to convert pdf to byte array in php laravel. I am using "IMUIS" which is accounting software solution and need to sending journal entries from laravel lumen to "IMUIS" for processing.But it gives the error after converting.

"Foutmelding": "Kan een object van het type System.String niet converteren naar het type System.Byte[]."

In english that means

"Error message": "Can not convert a System.String object to the System.Byte [] type."

The documentation is given here:

doc link

Here is the code for it.

public function saveJournal($values = '') {
    //echo "adasd";dd();
    $partnerKey = $values->input('Partnerkey');
    $omgevingscode = $values->input('Environmentcode');  
    $file = file_get_contents($values->file('Pdffile'));
    $str = base64_encode($file);
    $options = array(
        \WsdlToPhp\PackageBase\AbstractSoapClientBase::WSDL_URL => env('IMUIS_URL'),
        \WsdlToPhp\PackageBase\AbstractSoapClientBase::WSDL_CLASSMAP => ClassMap::get(),
    );
    $login = new \mysdk\ImuisSDK\ServiceType\Login($options);
    if ($login->Login(new \mysdk\ImuisSDK\StructType\Login($partnerKey, $omgevingscode)) !== false) {
        $sessionid = $login->getResult()->SessionId;
    }

    $array = [
        'BOE' => [
           'JR' => '2018',
           'PN' => '5',
           'DAGB' => 20,
           'REK' => 20032,
           'TEGREK' => '40',
           'FACT' => 0,
           'BTW' => 4,
           'BEDRBOEK' => 123.45,
           'DAT' => '08-05-2018',
           'OPM' => 'Anand testing from wsdl',
           'BEDRBTW' => 21,
           'FACT' => 0,
           'OMSCHR' => 'Testing from wsdl api',
           'BOEKSTUK' => 2018075
        ],
        'DIGDOS' => [
            'FILE' => $str
        ]
    ];

    $journaalpost = ArrayToXml::convert($array, 'NewDataSet');//convert array to xml string

    $create = new \mysdk\ImuisSDK\ServiceType\Create($options);
    if ($create->CreateJournaalpost(new \mysdk\ImuisSDK\StructType\CreateJournaalpost($partnerKey, $omgevingscode, $sessionid, $journaalpost)) !== false) {
        $jsonResponse = $create->getResult();
    } else {
        $jsonResponse = $create->getLastError();
    }
    return $jsonResponse;
}

and here is the response as well:

{
    "success": true,
    "result": {
        "CreateJournaalpostResult": false,
        "Journaalpost": "<?xml version=\"1.0\"?>\n<NewDataSet><BOE><JR>2018</JR><PN>5</PN><DAGB>20</DAGB><REK>20032</REK><TEGREK>40</TEGREK><FACT>0</FACT><BTW>4</BTW><BEDRBOEK>123.45</BEDRBOEK><DAT>08-05-2018</DAT><OPM>Anand testing from wsdl</OPM><BEDRBTW>21</BEDRBTW><OMSCHR>Testing from wsdl api</OMSCHR><BOEKSTUK>2018075</BOEKSTUK></BOE><DIGDOS><FILE>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</FILE></DIGDOS></NewDataSet>\n",
        "Primarykey": null,
        "Foutmelding": "Kan een object van het type System.String niet converteren naar het type System.Byte[]."
    }
}

There is a "bug" in the IMUIS software so it cant be possible to link a pdf file from php. Its may be done by Dotnet because its native language and the entire system built by it. Thanks to all of my SO friends for your efforts to helps me to find the issue, i have confirmed this information after call support. So in the future no one get stuck (afterall maybe end of 2018) :)