This error typically means you haven't got enough space to accommodate the temporary files PluralEyes needs to create to work with your project. PluralEyes needs about as much space to create temporary files as the project you've given it (ex. a 2GB project would need 2GB of space, 32GB project would need 32GB, etc.).
Head into the Preferences section of PluralEyes and adjust where the temporary files are stored to someplace with plenty of room for it work with.
- Another culprit is having temporary files on a remote or external drive. Try adjusting it to someplace on your local drive (like your user library or desktop), and make sure your local drive has plenty of space. Sometimes the behavior can also stem from read/write permission issues between your external/remote directories and programs like PluralEyes.
- The last culprit is newer or niche file types, like Sony FX3/AVC files. For this you'll need to transcode the footage to another file type prior to sending it through PluralEyes.
If none of these three suggestions help: