Error Opening Second Workbook

When you open a second Excel workbook, do you see an error message indicating that “PERSONAL.XLSB is already open?” If so, this problem has to do with how you are opening the second workbook.
There are two ways you can open workbooks: either from within Excel or from the operating system. Opening a workbook from within Excel is done by using the ribbon tools to open the file. Opening a workbook from the operating system is done if you double-click on a workbook icon.
Every time you open a workbook from the operating system, you are starting another instance of Excel. The error message appears only if you have a Personal.xlsb workbook on your system and only if you open a second workbook using the operating system method. The first time you open a workbook, it loads Personal.xlsb. The second time you open a workbook (remember-you are actually opening another instance of Excel) the program tries to load Personal.xlsb again. Since it is already open, you get the error.
The solution is to open the second workbook from within Excel, not from the operating system. Use the method of opening a workbook appropriate within your version of Excel and you won’t see the error message.
If you must open a second instance of Excel and you don’t want the error message, find the Personal.xlsb workbook using Windows’ Search feature. (Do this in Windows, not in Excel.) Right-click the file and choose Properties. In the Properties dialog box for the file, choose to make the file Read-Only. Once the file is read-only, you no longer get the error when you open up secondary instances of Excel. Why? Because the first instance doesn’t leave the file open due to it being read-only.
You can also bypass the error condition completely if you make one small configuration change in Excel. Follow these steps:

  1. Display the Excel Options dialog box. (In Excel 2007 click the Office button and then click Excel Options. In Excel 2010 and Excel 2013 display the File tab of the ribbon and then click Options.)
  2. Click Advanced at the left side of the dialog box.
  3. Scroll through the options until you can see the General group. (See Figure 1.)
  4. Figure 1. The General group of the Advanced options in the Excel Options dialog box.

  5. Make sure the Ignore Other Applications That Use Dynamic Data Exchange (DDE) check box is not selected.
  6. Click OK.

According to Excel’s help system, if the Ignore Other Applications check box is selected, then Excel won’t share DDE information with other applications. This isn’t all, however-it also affects how Excel starts when you double-click on a workbook in Windows and you already have Excel open. If the option is cleared (as it should be), then Excel starts the new workbook in the current instance of Excel. If it is selected (as it may be), then Excel tries to open a second instance of itself, and you will see an error message if you have a Personal.xlsb file on your system.