Each bit field type in Microsoft Dynamics CRM Online has two valid string values that are mapped within Microsoft Dynamics CRM Online to 1 and 0.
To prevent records from failing to import, you can either:
More information: Work with Data Maps.
Bit value mapping and import is not case-sensitive.
If you use the Import Data Wizard to create a new field of bit type, data will only be imported as True or False. This means your source data must have either a 1 or 0 in the column, and cannot use strings for the two values. After importing your data, you can customize the new bit field in Microsoft Dynamics CRM Online and change the values to strings. To work around this limitation, you might want to use Microsoft Dynamics CRM Online to create any new required-bit fields, and then use the Import Data Wizard to import data to the field.
Suggested Preparation in Source Files
To avoid import errors, make sure that the values for bit fields match the existing values in Microsoft Dynamics CRM Online, or manually edit the data map for the import to map your values to valid Microsoft Dynamics CRM Online values.
Mapping in the Data Map (optional)
In a data map, to map bit values, create a <PicklistMaps> section, with one <PicklistMap> for 1, and another for 0. For a detailed example showing the process, see How List Values Are Imported.