How do I fix Logic Pro Stem Splitter saying file doesn’t exist?

From your picture I can see, there is something wrong. Since you have selected the audio file in the Audio Browser, there should be the full path displayed, but the name is missing:

I would suggest to remove the file from the Audio Browser in Logic, save the Project, quit and re-open Logic, and put the file back into the project again. Or better work from a new, blank project.

And something else, don't reveal personal information when posting pictures in the internet. And learn how to take screenshots:

Take a screenshot on Mac - Apple Support

Good morning to you, Nateski,

You're welcome. I'm always happy to help and give back for all the help I've been given.

I always avoid using Special Characters, even if they are only Special Characters in a Shell script or some other language variant. As we see in Logic's version of MIDI Learn with Scripter, Logic creates JavaScript code. If an app such as Logic uses JavaScript or Shell scripts "under the hood", then we could get unpredictable results when it encounters our use of special characters. When I saw that your filename wasn't recognized, use of a Special Character was the first thing that came to mind.

I hope that helps clear up why I mentioned it.

John

Ben, since you mentioned screenshots, I have a question for you. My screenshots are always too big and the Moderator resizes them. Do you think he or she is just changing the settings in Preview to produce a smaller JPEG file? Some forums let you adjust your images by a scaled percentage, but I don't see that option here on the Apple Support Community Forums.

You might remember, too, that in the Bash shell an exclamation mark is used to show command line History. Apple switched from Bash to Z Shell a few versions of Mac OS ago, but the Bash shell is still installed for those who want to use it. I'm running into sites that are rejecting Apple's generated passwords just because they contain dashes. Code is getting more fussy about naming conventions, apparently.

My screenshots are always too big (...)

Screenshots can be resized within the post/reply. Click once on the screenshot, small square symbols should be displayed on the edge which you can use to change the size..

Make sure your audio file doesn't contain any special characters even no dot, comma....

Also make sure your file is located on a proper location on your hard drive not in the cloud.

Give Logic Pro Full Disc Access

An exclamation mark is a special character in UNIX operating systems. Mac OS is a UNIX operating system. Special characters have a reserved purpose and should be avoided in file names.

P.S. Nateski,

Never ever precede a filename with a period, as that makes the file a hidden file to the UNIX and UNIX-like operating systems (Linux).