Seems web driver today are quite not reliable. Originally it was OK to run the same browser with Stash_Helper, but now it will have an error.
So when you are using Chrome for Stash Helper, you need to close all other "chrome.exe", including the hidden ones.
The program will offer a choice to close them all, or you can click on "No" to close them yourself.
Plus other small startup fixes. The program might seems a little slow to start, but it's actually ok.