When you upload a CSV to the bulk import tool, you may see this error: "Oops! Your file was not successfully uploaded. Please make the corrections and try again. Can not decode file. Please ensure file is ASCII or UTF-8 encoded." This article walks through how to diagnose and fix it.
Diagnose
Check: File is not saved as UTF-8 CSV → Open your file. Check the format used when you last saved it. → If true: the file is saved as a standard Excel workbook (.xlsx), a non-UTF-8 CSV, or another spreadsheet format — proceed to Fix. → If not: confirm the file extension is .csv before uploading again.
Fix
Re-save from Microsoft Excel
- Open your file in Excel.
- Click File in the top menu.
- Click Save As.
- Choose a save location.
- Open the File Format (Mac) or Save as type (Windows) dropdown.
- Select CSV UTF-8 (Comma delimited) (.csv).
- Click Save.
- Return to the bulk import page and upload the new file.
Re-save from Google Sheets
- Open your file in Google Sheets.
- Click File in the top menu.
- Click Download.
- Select Comma Separated Values (.csv).
- Return to the bulk import page and upload the downloaded file.
> Google Sheets exports CSV files in UTF-8 by default.
What Resolution Looks Like
After uploading a correctly encoded file, the bulk import tool advances to the Preview import screen. No error banner appears.
If It Still Fails
Contact 15Five Support. Provide the following when you reach out:
- The exact error message text
- The file format you used when saving (e.g., "CSV UTF-8 in Excel for Mac")
- The operating system and spreadsheet application you used
Not Covered Here
This article covers only the UTF-8 encoding error. For all other bulk import steps and field formatting rules, see Add Users via Bulk CSV Import.