Python Script Expert Needed

I have a Python script intended to combine XML files into a single XML file, but it's currently producing incorrect output and crashing during execution. I need a skilled Python developer to help me fix these issues.

The error is:
Data written successfully.
Traceback (most recent call last):
File "/..../...../...../getproducts-5.py", line 42, in <module>
xml_tree = ET.fromstring(xml_response.text, parser=parser)
File "/usr/lib/python3.10/xml/etree/ElementTree.py", line 1342, in XML
parser.feed(text)
xml.etree.ElementTree.ParseError: not well-formed (invalid token): line 1, column 5387


Key Deliverables:
- Fix the script: The script should produce a single XML file as output, correctly combining the provided XML files.
- Stable Execution: The script should be able to run without crashing, handling various XML file formats.

Ideal Candidate Profile:
- Python Expert: Proficiency in Python and experience with manipulating XML files is a must.
- Debugging Skills: Ability to identify and resolve issues in existing code.
- Attention to Detail: A careful eye for pinpointing the reasons behind incorrect outputs.
- Understanding of XML: Familiarity with XML structure and how to correctly merge multiple XML files into one.

Please reach out with a brief overview of your relevant experience and how you would approach this specific issue.