What is the most likely cause of the error message during a bulk user import that indicates "A cell Value under [COLUMN NAME] is in an invalid format?"

The most likely cause of the error message indicating "A cell Value under [COLUMN NAME] is in an invalid format" is due to a misspelled or missing column value. The import process in Smartsheet requires that data adheres to the expected formats and constraints established for that particular column. If the value does not meet these standards—whether it is due to a typo, incorrect format, or being left blank—a validation error will be triggered.

This issue is particularly relevant because many columns in Smartsheet, such as for dates or numeric entries, have specific formatting requirements. For example, date columns expect values in a valid date format, and text fields may have character limits or restrictions. Therefore, if the data fails to conform to these pre-set criteria, it will be flagged as invalid during the bulk import process.

While other options address various user-related issues or email validity, they do not specifically pertain to the formatting of cell values, which is why they do not lead to the same error context reflected in the presented message. The focus here is on the integrity and correctness of the data being imported, which strongly supports that a misspelled or missing value is at the root of the problem described.