InDesign - a plug-n that supports the file format may be missing

[David R Saxby]

I am getting this error when I try to open an InDesign file I created in an earlier version. "Adobe InDesign may not support the file format, a plug-n that supports the file format may be missing, or the file may be open in another application." I cannot seem to find any help info on how to fix this. 

David

[Manan Joshi · Accepted solution]

Does this happen with just a particular file or all the files produced with the older version? If it is just a single file then it might be the case of file corruption. If it is indeed a corrupted file, you can email a copy of the document at idfile@adobe.com for the Adobe engineers to try and salvage the file for you. If the file is more than 10MB in size, upload it to a cloud service like dropbox and email the public access URL. There is no specified timeframe within which you can expect a revert from Adobe guys, so if time is of the essence and you won't mind a paid solution, try the following
https://markzware.com/products/file-recovery-service/

Edit:- The latest version of InDesign also comes with a corrupt document fixing service, it should prompt you for sending the file to the server when you try to open up a corrupt file.

-Manan