Excel Files saving in invalid file format

Question

I recently bought an Acer Switch 12 and installed Microsoft Office 2013 on it. 

Midway through last week, I've been encountering this error:

The error is not restricted to just the file above. It's been happening to most of the excel files I am constantly using, and I cannot determine the cause.

I have already run my antivirus, malware and spyware softwares, including Microsoft Safety Scanner, but the error still persists. I have had to restore my files several times already, to the point that any work I've done for a day sometimes get negated by the restoration. Can somebody help me with my problem?

Answer 1

@Kristine De Guzman,

The missing header was all it was lacking, after all.

The good news is that, this was easy (with the appropriate tool) to reconstruct it.

And the file is now fine for use in any Excel version.

I have uploaded it here : http://www.arstdesign.com/papers/2015\_GSN\_applicant\_tracker\_Copy.2.zip

(It's a 882 KB file. It's zipped that's why it's ten times smaller than yours)

Question is how to avoid this in the future. Answer begins by testing if this is a systematic problem in your current Excel 2013 install. You can answer the question by creating a trivial file.

Answer 2

Re:  Invalid file format

Kristine,

FWIW, both xl2010 and xl2003 would not open your file and instead displayed the invalid file format message.  I have the Compatibility Pack installed and can open .xls or .xlsx files in either Excel version.

[Edit]

Also, I tried opening the file in Firefox, Word 2003 and the Excel Viewer with no luck.

It does open in Notepad, but that doesn't make it useable.

I would try opening the file in Libre Office/Open Office (free ersatz Office versions)

(They are very large files)

[End Edit]

Hope you have a backup copy somewhere.

'---

Jim Cone

Portland, Oregon

free & commercial excel programs (n/a xl2013)

https://jumpshare.com/b/O5FC6LaBQ6U3UPXjOmX2

Hi James,

That's exactly my problem. Before I saved the file(s), they opened just fine on any version of MS Excel that I used. After updating the file on my Acer Switch12 w/ MS Excel 2013 & Win 8.1, I started encountering this error.

Luckily I have cloud storage with ability to recover previous versions, but recovering to an old file negates all the work I've already done.

Answer 3

@Kristine De Guzman,

Yes I have downloaded the file and begun the investigation. Here are the first comments :

• this is really a .XLS file internally according to the record sequences
• it seems to lack the first 250 bytes, and it is probably why Excel, in any version, complains that the file is not in a valid format. Fortunately most of this header stuff can be reconstructed.
• at the time of writing, it is unclear if this is all it lacks, or if there are more places like this.
• there is reason to believe this file can be recovered, if this is the former.
• as to why such a problem, you must have encountered a bug in Excel 2013, which apparently corrupts files it writes back as Excel 97-2003 files, if some unknown condition is met. 
• I have taken Excel 2013 SP1 and tried to reproduce this behavior with XLSX files of mine I converted as Excel 97-2003 workbooks : I couldn't reproduce it. 
• perhaps you can try to reproduce the problem with a trivial XLSX file. Convert it to a Excel 97-2003 workbook and see if it is trashed too.
• I am going to fill in the missing bytes, and see if I can get your file back working again.

Answer 4

Re:  invalid file format

@Stephane Zwel

Cleaning up that file was impressive!  Could you give a hint as to how it was done?

@Kristine De Guzman

You can cut your file size in half by removing all borders / interior colors and just displaying the grid lines on the "Applicants" sheet.

'---

Jim Cone

Answer 5

@James Cone

Hi,

I am using a BIFF editor of mine, which lets copy/paste individual BIFF records from files and automatically recompute record pointers on save.