When trying to open a Microsoft Office document (such as Word or Excel), you get this error:
A DDE error has occurred, and a description of the error cannot be displayed because it is too long. If the filename or path is long, try renaming the file or copying it to a different folder.
This DDE error occurs because the file name and file path in total contain more than 259 characters. To fix the A DDE error has occurred error, shorten the name of the file and / or move the file to the root of the C:\ drive to shorten the file path length.
If you are accessing the file from SharePoint, you will need to download the file before you are able to do this.