Spyder 4.1.3 Update: The issue is fixed!
(Tested on Python 3.8.3rc1, tornado 6.0.4)
If you come here still experiencing similar startup issues with Spyder: the first thing to try I'd suggest upgrade to Spyder version >= 4.1.3.
older version of this answer
workaround, tornado issue:
Modify the file ...\Python38...\Lib\site-packages\tornado\platform\asyncio.py;
add
import sys
if sys.platform == 'win32':
asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())
after the other import statements. Source: here on SO and also linked here. If I get this post on the tornado repo right, this is likely to be a pretty permanent workaround.
if also needed - workaround, pywin32 issue:
Modify the file ...\Python38\Lib\site-packages\jupyter_core\path.py;
add a line
import pywintypes
before import win32api in line 359. This modification is based on this post.
