E-Maculation

I am opening .sit files just fine in OS 9, but not so smoothly. It prompts me each time with the message:

Could not find the application program "StuffIt Expander" to open the document
To open the document, select an alternative program

and then IT HAS StuffIt Expander already highlighted, I choose Open, and it extracts the file.

Is there any way to get OS 9 to automatically associate my .sit files with StuffIt and open them right away, without the prompt?

The only thing I tried: I found StuffIt buried way down on my OS 9 hard drive, in Internet Applications. I did try copying it to the folder where my .sit file is, where I'm doing the extraction, but that didn't help.

You could try opening the Internet Config control panel and re-associating that version of Stuffit Expander with .sit files. It doesn't matter where the actual application resides as long as it's on the same drive as the system folder. Things get a bit trickier when applications are stored on a different drive/partition, but the file types and creators should still get registered correctly.

I just keep an Expander alias on my desktop and drag any compressed files onto it to expand them.

That second idea works great, and I would still like to try your first idea just to see if I can also get that to work.
I have an Internet Config Extension, ver. 2.0.5, in the extensions folder, in the system folder of my system 9.0.4
But I'm not seeing how to access it, and do the re-association you're talking about.
Just to make myself better and more aware, I'd appreciate more help to do what you describe. Thank you in advance.

You can set the association between file extension and application in the File Exchange control panel.