If you are able, try exporting it to IDML and open it again.
Is there a way to do this without having the file itself open?
Yes. There's a script that does just that. Give me a moment while I find it.
var _file = File.openDialog("InDesign-Datei"); // Selection of a file
if(_file != null)
var d = app.open(_file, false); // Open the file without showing it
d.exportFile(ExportFormat.INDESIGN_MARKUP, File(_file.fullName.replace(/.indd$/i,'.idml'))); // Export im IDML-Format
d.close(SaveOptions.NO); // Close without saving
And this is how to install it:
Unfortunately I'm still beachballing when I run the script. Is there a specific trick to exectuting the script or just running it from a blank document and selecting the offending file?
It should work with no document open. You just double click on it and a screen should pop up where you can select your file. At least that's the way it works on Windows. What Indesign version are you using, Mac/Windows?
CS6, mac. If I try to open the file outside of indesign I don't have an option to run it in indesign, only after effects, for some reason.
Unfortunately I'm still beachballing when I run the script.
You're probably out of luck. You could try running it directly from the ExtendScript ToolKit interface.