Python Error unhandled SystemError on execution of a SQL statement

(latest mariadb connector, Python 3.6.8, MariaDB-Server 10.3)

This is the error:

<built-in method fetchall of mariadb.connection.cursor object at 0x000001B6066C5808> returned a result with an error set Datei: D:\PythonApps\Finanz\Finanz_SQL.py, Zeile: 98

It is caused when executing this SQL Statement after a couple of other statements in the program run are executed without problems (Note: I had to reinstall Windows 10 and set up all new. But this program ran without any problems in my old environment. Also I can run this statement in HeidiSQL sucessfully):

def readAktiveAnlagenByTypes(conn, data): cur = conn.cursor() cur.execute("SELECT anlagestamm.AnlageNo, anlagestamm.Anlagebetrag, institute.InstName, " "anlagestamm.StartDat " "FROM anlagestamm INNER JOIN institute ON anlagestamm.InstitutNo = institute.InstNo " "WHERE anlagestamm.AStatus = 1 AND anlagestamm.TypNo = ? AND anlagestamm.UnterTypNo = ? " "ORDER BY anlagestamm.TypNo, anlagestamm.UnterTypNo, institute.InstName", data) result = cur.fetchall() return result

I have not idea what could be wrong. If a mistake in the statement, I would have received another error.