python xlrd unsupported format, or corrupt file.

You say:

The file doesn't seem to be corrupted or of a different format.

However as the error message says, the first 8 bytes of the file are '<table r' ... that is definitely not Excel .xls format. Open it with a text editor (e.g. Notepad) that won't take any notice of the (incorrect) .xls extension and see for yourself.

Try to open it as an HTML with pandas:

import pandas as pd
data = pd.read_html('filename.xls')

Or try any other html python parser.

That's not a proper excel file, but an html readable with excel.