Valeria Maria Tafel 

You need to provide more information, such as:

• path to the project package (some reason why it might be considered inaccessible)
• name of the project package (looking for special chars for example)
• type of project package (Trados Studio, WorldServer, TMS?)
• version of Trados Studio it came from?
• how are you trying to open it?
• did you save it to a sensible location before trying to open it?

Valeria Maria Tafel 

And while I'm at it... I also get problems like this from time to time.  This time using a folder I have set up to save video recordings because I always have problems with them going into OneDrive:

Even here I had a problem this morning and could not save to it.  Somehow, and I can only put this down to some recent update, my folder became read only... which isn't very helpful!!

So perhaps worth checking that as well!

Thank you, Paul, for the time spent answering to this. Eventually I simply told my client that the package could not be opened and it was probably a matter of excessively long file name (although I don't understand where all that length was, not being visible - even by setting the view of filename extensions and hidden elements...). Anyway, it's resolved for this time.
Another issue I am having since I'm using Studio 2024 is that sdlxliff files are often "disconnected" from their original Word file and I have to "reconnect" them manually by opening the relevant Word file... Fortunately I found the solution and I use it, but this never happened to me before, with all the previous Studio versions...