It may happen that when the Show output button is pressed Excel will start but indicate that it cannot find the file. The message will look something like this:

The error is caused by the path (folder description + file name) being longer than 260 characters. The limitation is unavoidable in Windows versions earlier than Windows 10, release 1067 (around May 2016) but can be changed with some difficulty in later versions.

The simple fix is to change the save folder to something that has a shorter path.