In the file ucs-school-import-error.log yu see following entries:
2020-06-03 15:35:03 INFO First line of u'/var/lib/ucs-school-import/jobs/2020/96/school.csv': '\xef\xbb\xbfGUID;Name;Vorname;Klasse\r\n'
At least the prefix with the “\xef[…]” looks strange.
The above characters are “Byte-Order-Marks”. Some tools create them in order for any reading tool to get the correct data.
However, Importer knows these characters and treads them correctly.
This is not a reason for an error.