Why is Excel saying “The format of the [logfilename].xls doesn’t match. The file could be corrupted…” ?

Our Excel files are generated using HTML web formatting.  Microsoft recently updated newer versions of Excel to issue a warning if a file is in HTML web format but has an .xls extension.

The file is safe to open.  You can click “Yes” and the file will display.  You can also download the file in PDF to prevent this Microsoft Excel warning from appearing.