The error message suggests that there is a problem with the format of the CDB list file you are trying to upload. Here are some steps you can take to resolve the issue:
Check the format of the CDB list file: Make sure that the file format is correct and follows the specifications for CDB list files. You can refer to the documentation
here for the correct format.
Check for errors in the CDB list file: Sometimes, errors in the CDB list file can cause issues during upload. Check the file for any syntax errors, missing or extra fields, or other issues.
Check the file encoding: Also, as stated in the documentation, the cdb list is a plain text file so you should make sure the file is encoded in UTF-8, as other encodings can cause issues during upload.