Old Cubase project Sound Designer 2 files won't open

I’ve got some 20+ year old projects that open in Cubase 13 Pro but somehow along the way some of the audio files got corrupted and won’t open. They show up as Sound Designer 2 files. (I always worked with AIFF back then.) The file name has no suffix, but simply ends with 000 or 001. I’ve tried opening in WaveLab but it doesn’t recognize them either. I’ve used an online conversion tool but it didn’t work. Any suggestions how to open these files and/or convert to wav files?

If I recall correctly Sound Designer II was a software from Digidesign, now part of Avid. It pre-dated Pro Tools.

Not sure how that helps solve the problem Johnny. These files were not created in SD II they were created in Cubase. Somehow over the course of several updates some of the AIFF files in the project were converted and/or corrupted. It’s puzzling since the other files in the project still work. I’ve tried adding .aiff to the file name but that didn’t work either. Wondering if there’s a way to read these files somehow, and convert them to wav.

I’d probably try opening as a raw file in whatever audioeditor you use that supports this. Audacity does/did. Reaper maybe?
If you can get them open, resave them as aiff.

At some point after 2013, I recall there being news that the codec behind the SDII format would no longer be distributed and/or maintained. The post-production facility I worked at spent a couple weeks converting all SDII files. It was a mess.

Interesting. Part of the mystery of my situation is how the AIFF files converted into SDII files.

I’m not sure I can help on that front. As you mentioned, these are old sessions. It’s possible they were saved using the SDII codec in an AIFF wrapper, and it hasn’t been until now that it mattered.

What I tried to hint at is that back in the days SDII was somewhat of a standard for audio files and had native support within Cubase. SDII is no longer an active format for several years now and contemporary version of Cubase do not support it anymore.
Either you find an old version of Cubase, which supports SDII or you find a different application which allows conversion of SDII to AIF or WAV.