ERROR UPLOAD XML FILE - PYTEST - ZEPHYR SCALE

Hello guys,

I am using pytest and have generated an xml file to import into zephyr. I tried to upload it manually and tried with the REST API, but with no success both ways. 

Code that made me generate the xml file (I got this code from Smartbear - Configuring pytest to output JUnit XML results file): 

pytest --junitxml=output/junitxml_report.xml

Error manually: The uploaded file cannot be interpreted. Your content is invalid. Please try again by uploading a valid file.

My code with API Rest:

def test_upload(self):
    url = 'https://api.zephyrscale.smartbear.com/v2/automations/executions/junit?projectKey="BST"&autoCreateTestCases=true'
    headers = {'Authorization': 'Bearer ' + 'eyJ0e...CONTINUE'}
    fhir = open('junitxml_report.xml', 'rb')
    response = requests.post(url, headers=headers, files={"archive":(fhir)})
RESPONSE: {'errorCode': 400, 'message': 'createJUnitExecutions.projectKey: must match "([A-Z][A-Z_0-9]+)"', 'status': 'Bad Request'}