I am using Tkinter in my program, and at a point I use a button to open a file by running a function with the following code:
def UploadAction(event=None):
     global filename
     filename = filedialog.askopenfilename()
     filename = [filename]
return filename
However, when I run this function, it causes Python to freeze. Apparently there have been bugs like this before in previous versions, and this wasn't a problem on 3.7, which makes me suspect that this is a bug rather than a fault on my end. Would you be able to release an update to fix this bug? Thanks.

Can you provide a minimal, self-contained, example of a program that demonstrates this behaviour in 3.8, but works in 3.7. It's not really possible to determine what the issue might be without a means of reproducing the problem.

I've just tried it on Windows 10 with Python 3.8 64-bit and Python 3.8 32-bit without issue.

Just tried to do that and found out that IDLE also crashes when opening a new python file, not just when using that code. Maybe it's a problem just with my computer? I am running python on Windows with an AMD Ryzen 5 processor with 8GB RAM if it helps.

What is your OS? Is it macOS specific issue?

No, it is an issue with Windows. I think it might only be a problem with my computer though, maybe the fact that I have an AMD processor might have something to do with the problem?

Processor type is far less likely than a shell extension.

Do you have anything like DropBox/Tortoise???/etc. installed?

I have dropbox installed, would that be what's causing the problem?

Potentially. I don't have it installed, so I can't test, but I know in the past it added a shell extension that would display overlays over files it controlled.

That shell extension will be loaded into most system file picker dialogs, and at various points has executed Python code. I doubt they're on 3.8, but it's possible that there is some kind of conflict.

Can you try uninstalling or disabling its shell integration?

How would I do that?

Temporarily uninstalling your Dropbox client is the easiest way.

filedialog.askopenfilename returns 'Open(**options).show()'.  IDLE's File => Open (^O) calls Open and show directly.  It continues to run on all versions on my machine (and presumably those of numerous others).  I have TortoiseGit now and only recently removed TortoiseHG, so those two seem well-enough behaved.  This is almost certainly not a cpython issue, but it would be good to know where the problem lies.

In case it helps, I have the same problem. Running python 3.8.8 on Windows 10, and any MWE doesn't work, e.g.:

from tkinter import filedialog
from tkinter import *

root = Tk()
root.filename =  filedialog.askopenfilename(initialdir = "/",title = "Select file",filetypes = (("jpeg files","*.jpg"),("all files","*.*")))
print (root.filename)

I just get the spinning circle and unresponsive dialog. I have quite a few shell integrations so uninstalling them is not ideal.