Keyword and target imports can fail for several reasons. Please make sure to follow these tips before importing your file:
Spreadsheets must be smaller than 10MB in file size and have fewer than 5,000 lines.
Your file must be saved as a Windows Comma Separated CSV.
Spreadsheet data must be formatted according to the sample template or the exported CSV from your campaign's Keywords or Targets tab. Any deviation from the compatible formatting can cause your import to fail.
Sample spreadsheets for keyword and target imports are available here:
TIP: We strongly suggest waiting until the previous import has completed before uploading another file to the same campaign.