The CsvReader `classes` attribute in the configuration is supposed to allow the replacement of classes like the reader classes derived from `BaseReader`. As `filename` argument was not passed to the reader classes besides specifically for the `CsvReader` using custom reader classes was not possible.
Errata updates for UCS@school 5.0 v5 have been released. https://docs.software-univention.de/ucsschool-changelog/5.0v5/en/changelog.html https://docs.software-univention.de/ucsschool-changelog/5.0v5/de/changelog.html If this error occurs again, please clone this bug.