Word: Compare documents not working

April 30, 2012

I’ve been working with Word for a couple of decades (!) now, but still it surprises me with what it can do. There are some things I rarely use (such as mail merge), so I’m not familiar with how they work, and then there are other things I just didn’t even realize were in Word — like ‘compare documents’ — because I’ve never had any need to use those features.

However, a work colleague uses Word’s compare function quite often and was having trouble when comparing two versions of the same document. She asked me for help, and then I discovered the value and the speed of the ‘compare’ function.

But first, I got the same error as her (“Word was unable to compare the documents”) when I tried to compare these documents on my computer, thus eliminating her PC as the problem, but once I’d changed some settings, everything worked superbly.

Here’s what I did:

  1. I first tried to compare the two documents without making any changes to them and keeping all the default settings for the comparison. To compare two documents, go to the Review tab, Compare group, click the Compare button, then select the Compare… option.
  2. I browsed to the two documents, left all the settings as they were, then clicked OK.
  3. After a minute or two of processing, I got the same error that my colleague got.
  4. Document A (the original version) had been created in Word 2003 and so was a *.doc document. To eliminate that as the reason for the error, I saved it as a *.docx document. This reduced the file size considerably (a side bonus).
  5. I also accepted all track changes in Document A, then saved Document A under a different name (just so I didn’t mess up the original!).
  6. Document B (the revised version, and already a *.docx document) also had Track Changes turned on, so I accepted all those and saved that document with a new name too.
  7. I then ran the compare again, again with all the default settings selected, but still I got the error.
  8. I tried again, this time clearing all the check boxes for the things that didn’t need to be reported as a change in the final document. This time it worked!

For this 250p document, the comparison took very little time (maybe a minute or so) and I got a document that showed all the changes I’d selected to report in the new document. I still had to accept the formatting changes for the tables and the cross-reference field changes, but that was all.

If you ever get this error message when trying to compare document versions, turn off some of the default selections for comparison and run it again.

For the reasons why there were still table formatting changes marked even though I’d turned off formatting, see this blog post that details the ‘hierarchy’ of what gets turned on and off when you change these settings: http://blogs.office.com/b/microsoft-word/archive/2009/02/17/test2903298.aspx

[Links last checked April 2012]


  1. Thank you!

  2. I had the same problem and came here. This didn’t solve my problem though :(. I tried hotfixes and registry edits – nothing. Turns out Word has a problem with the length of tables. I unchecked the “Tables” box (top, right hand column) and hey presto worked for me.

  3. this was fantastic. i uncheck all the option. thank you!

  4. So awesome. Such uncheck tables and you are golden.

  5. When I do a doc compare, I can’t stay on the page I’m editing. Word keeps going to the end of the document and I have to find my way back to where I was working. Suggestions? Word 2010.

  6. Clearing non-essential checkboxes DOES help. It counteract “not respond” message every time when I click anywhere on Word 2016. Frequency of hanging reduces when Revisions window turn off, too. I am working on 311 pages novel manuscript.

  7. Thanks for the tip! I had the same issue (can’t compare) and whittled away the options until it worked!

  8. Thanks, this was very helpful and just saved me hours of work!

  9. Unchecking Tables works. Checking Tables and unchecking all other options works. Checking Tables and checking all options does not work.

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