Banks change their formats from time to time. Sometimes the file is converted, but a date is not recognized correctly, for example. In this case, Datev issues a message when checking via the "Check input" button in the "Bank account turnover settings" window. (you can access our main page here: https://ckonverter.de/ )
an error message.
For a quick remedy, you can open the converted file (please perform a conversion in "DATEV Bankformat" format) and look in the column and field of the error message to see if there is an unusual value. Sometimes it is just a date that has been incorrectly recognized.
Please send us the original file and the converted file afterwards using the following form:
English 
German