[bug] XMLSyntaxError: Start tag expected, '<' not found, line 1, column 1

[fhjgch]

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• Read the relevant sections of the documentation

• Browse the tutorials and tests for usefull code snippets and examples of use

• Reproduced the issue after updating with pip install --upgrade pandapower (or git pull)

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Reproducible Example

See `cim2pp` notebook in tutorials:

# folder_path points to the directory where the CIM .zip-Files are stored:
folder_path = os.path.join(os.getcwd(), 'example_cim')

# cgmes_files is a list containing paths to both files needed for the CIM converter:
cgmes_files = [os.path.join(folder_path, 'CGMES_v2.4.15_SmallGridTestConfiguration_Boundary_v3.0.0.zip'),
               os.path.join(folder_path, 'CGMES_v2.4.15_SmallGridTestConfiguration_BaseCase_Complete_v3.0.0.zip')]

for f in cgmes_files:
    if not os.path.exists(f):
        raise UserWarning(f"Wrong path specified for the CGMES file {f}")

net = cim2pp.from_cim(file_list=cgmes_files, use_GL_or_DL_profile='DL')

print('Conversion successful')

Issue Description and Traceback

Reading of the XML files fails with following error: XMLSyntaxError: Start tag expected, '<' not found, line 1, column 1.
This only happens to some of the files stored in example_cim, not all of them.

It seems that the encoding of the files is the problem, as some are encoded in 'utf-8' while others in 'utf-8-bom'. After conversion of all files into 'utf-8' the file import was successful.

Expected Behavior

Message: "Conversion successful"

Installed Versions

INSTALLED VERSIONS

commit : 0691c5cf90477d3503834d983f69350f250a6ff7
python : 3.11.8
python-bits : 64
OS : Windows
OS-release : 10
Version : 10.0.22631
machine : AMD64
processor : Intel64 Family 6 Model 186 Stepping 3, GenuineIntel
byteorder : little
LOCALE : English_United Kingdom.1252

pandas : 2.2.3
numpy : 2.0.2
pytz : 2024.2
dateutil : 2.9.0.post0
pip : 23.2.1
IPython : 8.28.0
bs4 : 4.12.3
jinja2 : 3.1.4
lxml.etree : 5.3.0
matplotlib : 3.9.2
numba : 0.60.0
scipy : 1.13.1
tzdata : 2024.2

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[KS-HTK]

@heckstrahler @mrifraunhofer I had the same Issue.

[KS-HTK]

The issue seems to be the encoding passed to XMLParser object. According to help(etree.XMLParser) this should be a libiconv encoding name, suggesting that 'UTF-8' is a valid name. But if i ommit the encoding keyword there is no longer any issue.

What is the reason for overriding the encoding?

Relavant code section: cim_classes.py Line 488

# Leads to error
parser = etree.XMLParser(encoding='UTF-8', resolve_entities=False)
xml_tree = etree.parse(file, parser)

# No error
parser = etree.XMLParser(encoding=None, resolve_entities=False)
xml_tree = etree.parse(file, parser)

print(xml_tree.docinfo.encoding)
# prints: 'UTF-8'