Edit in Office with Office 365 generates "Upload Failed Error"

Issue Summary

When saving changes to a file in Office 365 you'll receive an error:

UPLOAD FAILED Your file wasn't uploaded because your chagnes can't be merged with changes made by someone else.

Environment

Office 365

Steps to Reproduce

1. On a machine with Office 365 open a document from Confluence via "Edit in Office"
2. Make changes to the file
3. Save the file

Expected Results

The file is saved and uploaded to Confluence. A new version of the file is available

Actual Results

You'll run into the error in Office:

UPLOAD FAILED Your file wasn't uploaded because your chagnes can't be merged with changes made by someone else.

There are no errors in the Confluence logs

Workaround

To workaround this bug you have two options:

1. Select Save a Copy
   1. Save a copy to the location designated
   2. The file will be properly uploaded to Confluence with a new version
2. Select Discard Changes
   1. Any changes you've just made will be removed
   2. Make the desired changes again
   3. Save the file
   4. This time the file will be properly uploaded with a new version
   5. Note, the Office document will not close automatically after the upload in this scenario