Streasmlit app doesn't load on customer machine

This looks like a firewall issue where some network requests are blocked. Can you post a screenshot of the Network tab in chrome?

@Anders Hafreager  Thanks for the info. 

I just had a call with the customer and asked him to reproduce the issue live and to take some screenshots.

First a screenshot of the network tab:

Then i asked him to Empty Cache and Hard reload the page. After this the behavior changed a bit 
Now het got the following error message:

Traceback (most recent call last):
  File "/lib/python3.12/site-packages/micropip/_commands/install.py", line 142, in install
    await transaction.gather_requirements(requirements)
  File "/lib/python3.12/site-packages/micropip/transaction.py", line 55, in gather_requirements
    await asyncio.gather(*requirement_promises)
  File "/lib/python3.12/site-packages/micropip/transaction.py", line 68, in add_requirement
    await self.add_wheel(wheel, extras=set(), specifier="")
  File "/lib/python3.12/site-packages/micropip/transaction.py", line 234, in add_wheel
    await wheel.download(self.fetch_kwargs)
  File "/lib/python3.12/site-packages/micropip/wheelinfo.py", line 129, in download
    with zipfile.ZipFile(io.BytesIO(self._data)) as zf:
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/lib/python312.zip/zipfile/__init__.py", line 1339, in __init__
    self._RealGetContents()
  File "/lib/python312.zip/zipfile/__init__.py", line 1406, in _RealGetContents
    raise BadZipFile("File is not a zip file")
zipfile.BadZipFile: File is not a zip file

There are the 403 - Forbidden error codes in the network traffic which indicate a firewall/proxy issue​​​

Yes, I agree. Those requests are to Python packages that Streamlit needs to be able to run and are likely blocked by firewall.