When a formula in a table cell is incomplete, contains invalid cell references, or is otherwise incorrect, or when an import operation creates an error condition in a cell, Numbers displays an icon in the cell. A blue triangle in the upper left of a cell indicates one or more warnings. A red triangle in the middle of a cell means that a formula error occurred.

To view error and warning messages:

Click the icon.

A message window summarizes each error and warning condition associated with the cell.

To have Numbers issue a warning when a cell referenced in a formula is empty, choose Numbers > Preferences and in the General pane select "Show warnings when formulas reference empty cells."

Was this page helpful? Send feedback.