The following worksheet issues cause a significant loss of functionality:

Issue Solution
This workbook contains data in cells outside of the row and column limit of the selected file format. Data beyond 256 (IV) columns by 65,536 rows will not be saved. Formula references to data in this region will return a #REF! error. In Excel, the worksheet size is 16,384 columns by 1,048,576 rows, but the worksheet size of earlier versions of Excel is only 256 columns by 65,536 rows. Data in cells outside of this column and row limit is lost in earlier versions of Excel.

In the Compatibility Checker, click Find to locate the cells and ranges that fall outside of the row and column limits, select them, and then place them within the column and row limits or on another sheet by using the Cut and Paste commands.

For more information, see:

This workbook contains dates in a calendar format that is not supported by the selected file format. These dates will be displayed as Gregorian dates. In Excel, you can create custom international calendar formats, such as Hebrew Lunar, Japanese Lunar, Chinese Lunar, Saka, Zodiac Chinese, Zodiac Korean, Rokuyou Lunar, and Korean Lunar. However, these calendar formats are not supported in earlier versions of Excel.

To avoid loss of functionality, you may want to change the calendar format to a language (or locale) that is supported in earlier versions of Excel.

For more information, see:

This workbook contains dates in a calendar format that is not supported by the selected file format. These dates must be edited by using the Gregorian calendar. In Excel, you can apply a non-Western calendar type, such as Thai Buddhist or Arabic Hijri. In earlier versions of Excel, these calendar types can only be edited in Gregorian.

To avoid loss of functionality, you may want to change the calendar format to a language (or locale) that is supported in earlier versions of Excel.

For more information, see:

This workbook contains more cells with data than are supported in earlier versions of Excel. Earlier versions of Excel will not be able to open this workbook. In Excel, the total number of available cell blocks (CLBs) is limited by available memory. In earlier versions of Excel, however, the total number of available CLBs is limited to 64,000 CLBs in an instance of Excel.

A CLB includes 16 worksheet rows. If all rows in a worksheet contain data, you would have 4096 CLBs in that worksheet, and you could have only 16 of such worksheets in a single instance of Excel (regardless of how many workbooks you have open in Excel).

To ensure that the workbook does not exceed the 64,000 CLB limit and can be opened in earlier versions of Excel, you should work in Compatibility Mode in Excel after you save the workbook to Excel 97-2003 file format. In Compatibility Mode, Excel keeps track of the CLBs within the active workbook.

For more information, see:

The following worksheet issues cause a minor loss of fidelity:

Issue Solution
Earlier versions of Excel do not support color formatting in header and footer text. The color formatting information will be displayed as plain text in earlier versions of Excel. In Excel, you can apply color formatting to header and footer text. You cannot use color formatting in headers and footers in earlier versions of Excel.

In the Compatibility Checker, click Fix if you want to remove the color formatting.

This workbook contains worksheets that have even page or first page headers and footers. These page headers and footers cannot be displayed in earlier versions of Excel. In Excel, you have the option to display different header and footer text on even pages or on the first page. This option is not available in earlier versions of Excel. Even page or first page headers and footers cannot be displayed in the earlier versions, but they remain available for display when you open the workbook in Excel again.

If you frequently need to open a workbook in an earlier Excel file format, you may want to stop using even or first page headers or footers for that workbook.

For more information, see:

Some cells or styles in this workbook contain formatting that is not supported by the selected file format. These formats will be converted to the closest format available. In Excel, different cell formatting or cell style options are available, such as special effects and shadows. These options are not available in earlier versions of Excel.

You can accept the closest available format that is applied when you continue saving the workbook, or you can change or remove a cell style that is not supported before you save the workbook in an earlier Excel file format.

For more information, see:

This workbook contains more unique cell formats than are supported by the selected file format. Some cell formats will not be saved. In Excel, you can use 64,000 unique cell formats, but in earlier versions of Excel, you can only use up to 4,000 unique cell formats. Unique cell formats include any specific combination of formatting that is applied in a workbook.

For more information, see:

This workbook contains more unique font formats than are supported in the selected file format. Some font formats will not be saved. In Excel, 1,024 global font types are available, and you can use up to 512 of them per workbook.

For more information, see: