When you upload a file to Nosto to bring your own customer data, it must respect a CSV UTF-8 - comma separated format and the maximum size per file is 25MB.
Some of the most frequently seen data formatting errors include:
The file is not comma separated but semicolon separated
The email addresses are not reported accordingly e.g firstname.lastname@example.org or firstname@gm a il.com or firstname@"gmail.com
You can find all information on how to correctly format your .CSV file here.
As additional resources, we recommend you to respect the following guidelines to create a CSV file from scratch: https://www.wikihow.com/Create-a-CSV-File