I am validating a an XML file which contains:

<TEST />

and I validate like the following:

import lxml as l
def validate(xml_path, xsd_path):
    schema_doc = l.parse(xsd_path)
    schema = l.XMLSchema(schema_doc)
    xml_doc = l.parse(xml_path)
    result = schema.validate(xml_doc)
    if result:
        return True
    else:
        print("Validation error(s):")
        for error in schema.error_log:
            print(xml_path + " | Line {}: {}".format(error.line, error.message))
    return False
validate(xml_path, xsd_path)

But I get an error pointing to the line where there is an empty tag <TEST /> and I don’t know why.

The complete error message is this:

Line 381: Element '{namespace}TEST': [facet 'pattern'] The value '' is not accepted by the pattern '[a-zA-Z][a-zA-Z0-9_]*'.

what is this exactly?

I tried to find out why, but with no clue really as the empty element is a valid one.