If you are adding contacts by uploading a spreadsheet or CSV, there are a few reasons why your contacts may not get saved. There are certain fields that are mandatory while importing contacts e.g. email address or any other field which are marked as mandatory by the Administrator. If these fields aren't present or have the wrong format, those contacts will not be uploaded.

In summary, contacts will not get added if:

-  Mandatory fields aren't mapped from the CSV/ XLS file to the contacts fields or

- The format of the field is wrong (e.g. email field is mapped to a phone number field) or

- Mandatory fields are empty for a contact