I was working on a file yesterday and I saved it as an InDesign Markup Document (.idml) document. However, I tried to open that file today and it didn't open and an InDesign pop-up window opened saying: "cannot open file "name .idml". Adobe InDesign my not support the file format, a plug-in that supports the file format may be missing, or the file may be opened in another application". Given the fact that the file is not opened in another application, and I was working on CS6 and saved the file as (CS4 or later).
What might the problem be? or what might that missing plug-in be?
This is the pop-up window that I'm seeing when i open the file.
Try installing the CS6 8.1 update. I think it addresses this problem. The interface in your screen shot doe not look like CS6 to me, however, as the dark interface was not introduced until version 9 (CC), so you should be sure that you have the latest update for each of your versions. Use the Gear icon on the CC Desktop App to quit the app, then restart it and let it update before checking for program updates.
That is NOT CS6. Why did you save as IDML and can you open the original INDD file?
Are you sure that it is really an IDML and not an INDD with the wrong extension?
What vesion do you have? CC or CC2014?