You receive a "Too many different cell formats" error message in Excel

In Microsoft Excel, when you format a cell or a range of cells, you may receive the following error message:

This problem occurs when the workbook contains more than approximately 4,000 different combinations of cell formats. A combination is defined as a unique set of formatting elements that are applied to a cell. A combination includes all font formatting (for example: typeface, font size, italic, bold, and underline), borders (for example: location, weight, and color), cell patterns, number formatting, alignment, and cell protection.

NOTE: If two or more cells share exactly the same formatting, they use one formatting combination. However, if there are any differences in formatting between the cells, each cell uses a different combination.

To resolve this problem, simplify the formatting in the workbook. For example, the following are suggestions for simplifying formatting:

• Use a standard font.
  
  Using the same font for all cells reduces the number of formatting combinations.
• If you use borders in a worksheet, use them consistently.
  
  NOTE: If you apply a border to the right side of a cell, it is not necessary to apply a border to the left side of the cell that is to the right because the borders overlap.
• If you apply patterns to the cells, remove the patterns by clicking No Color in the Patterns tab of the Format Cells dialog box.

NOTE: After you simplify or standardize the formatting in the workbook, save, close, and then reopen the workbook before you apply additional cell formatting.

In most cases, the limit of approximately 4,000 different formatting combinations for a single workbook is sufficient. This problem is likely to occur only when the workbook contains a large number of worksheets that use different formatting, or when a large number of cells are all formatted differently.