There is a bug in the handling of MSO files. It is related to the fact the MSO creates a temporary file when opening an OpenXML file, with a ~$ prefix and a standard "..x" extension, that OmegaT tries to unzip, and fails.
For some reason, even though the file should be handled my the OmegaT MSO filter, it is eventually passed to the Okapi filter that chokes on it, and OmegaT refuses to (re)open the project.
13459: Erreur: net.sf.okapi.common.exceptions.OkapiIOException: Error opening zipped input
The OmegaT filter has fixed that by adding **/~$* to the excluded files list:
Would it be possible to have something similar on the Okapi side ?
Jean-Christophe Helary @brandelune