Likely a bug due to update to prompt toolkit 3.
You can try to downgrade to prompt_toolkit 2 to avoid this; or run from github/master branch and modify the source to print the stack trace when this happens to debug.

Likely a bug due to update to prompt toolkit 3.
You can try to downgrade to prompt_toolkit 2 to avoid this; or run from github/master branch and modify the source to print the stack trace when this happens to debug.

@Carreau that's a good idea - I also tried looking through prompt-toolkit's current issues but nothing relevant seemed to stand out.

Downgrading prompt-toolkit from 3.0.2 to 2.0.2 did the trick for me. 2.0.1 caused a problem.

7.10.2 has been released; let me know if it fixes this issue.

7.10.2 has been released; let me know if it fixes this issue.

Some quick tests I did suggested that the issue had been resolved at first, but then a new/similar issue popped up:

Once again, this was with the following package info:

{'commit_hash': 'f7f2eae63',
 'commit_source': 'installation',
 'default_encoding': 'utf-8',
 'ipython_path': 'C:\\Users\\Yannis.Katsaros\\AppData\\Local\\Continuum\\anaconda3\\envs\\aoc\\Lib\\site-packages\\IPython',
 'ipython_version': '7.10.2',
 'os_name': 'nt',
 'platform': 'Windows-10-10.0.17134-SP0',
 'sys_executable': 'C:\\Users\\Yannis.Katsaros\\AppData\\Local\\Continuum\\anaconda3\\envs\\aoc\\python.exe',
 'sys_platform': 'win32',
 'sys_version': '3.8.0 (default, Nov  6 2019, 16:00:02) [MSC v.1916 64 bit '
                '(AMD64)]'}

7.12.0, fresh IPython install, edge-case?

I initially thought all was good, as when I freshly install IPython and it's dependencies, I like to do something like import os and repeat the command about 30 or 40 times, as this seems fairly reliable. But this time, it only (coincidentally?) happened upon creation of an object I had not previously used before.

I don't know the super technical details, but it seemed odd that it happened on an event it had never encountered before (personally, on my computer). Dunno. Not important. But providing the above data is important, so cheers, great work, love you guys/gals, and I'll just downgrade prompt-toolkit to 2.0.2 in the meantime.

EDIT: By the way, I repeated those 18 lines preceding that import, and it didn't do it that time. Too bad it wasn't repeatable.

EDIT 2: Here ya go.

{'commit_hash': '8bda98619',
'commit_source': 'installation',
'default_encoding': 'utf-8',
'ipython_path': 'C:\Users\tk13x\AppData\Local\Programs\Python\Python38\Lib\site-packages\IPython',
'ipython_version': '7.12.0',
'os_name': 'nt',
'platform': 'Windows-10-10.0.18362-SP0',
'sys_executable': 'C:\Users\tk13x\AppData\Local\Programs\Python\Python38\python.exe',
'sys_platform': 'win32',
'sys_version': '3.8.2rc2 (tags/v3.8.2rc2:777ba07, Feb 18 2020, 09:11:15) [MSC '
'v.1916 64 bit (AMD64)]'}

I'm only just now noticing I was not on the current version. My apologies.

I'm only just now noticing I was not on the current version. My apologies.

No need, 7.13 was release 2 days ago, so at the time of your comment you were on the lastest stable.

Did this get fixed in 8.0.0? I can't seem to reproduce it at all.

Edit: Nevermind, user error, apparently.

I don't know what the status on this issue is, but I came across something in a BPO. I realize this isn't a long-term solution, but until ProactorEventLoop is up to the task, this is what I've done to patch my iPython (7.13.0 & 8.0.0dev, Windows10, 64 bit, Python 3.8.1):

if sys.platform == 'win32':
  asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())

in ..\site-packages\IPython\terminal\interactiveshell.py

I'm not experienced enough to know, or even suspect, if this could cause other issues elsewhere, but we'll cross that bridge when we get there.

So, after my last comment, I had ended up reinstalling python for other reasons, but I noticed that iPython was no longer producing this error. I continued on, as normal.

I ran into this again, under some interesting circumstances.

The context (not important): I was looking for sudoku strings, and wasn't trying to flood my terminal with 20k+ lines from the page.

What seems relevant here, is something I had briefly mentioned before, about it only happening for an action that I had not previously done before, ever (at least in iPython. i may have done this in a script, but idk). I don't use requests that often, and this is the first time I used .raw. But this is also true of many commands I've used recently. I (probbaly naively) assume there's a specific circumstance in which this seems to happen.

{'commit_hash': 'd0b255042',
'commit_source': 'installation',
'default_encoding': 'utf-8',
'ipython_path': 'C:\Users\tk13x\AppData\Local\Programs\Python\Python38\Lib\site-packages\IPython',
'ipython_version': '7.13.0',
'os_name': 'nt',
'platform': 'Windows-10-10.0.18362-SP0',
'sys_executable': 'C:\Users\tk13x\AppData\Local\Programs\Python\Python38\python.exe',
'sys_platform': 'win32',
'sys_version': '3.8.2 (tags/v3.8.2:7b3ab59, Feb 25 2020, 23:03:10) [MSC '
'v.1916 64 bit (AMD64)]'}

I don't know. Just thought I'd share. In the event that it would be beneficial to be sitting in front of this terminal (albeit a few lines later), I've left this terminal open and minimized it. (You know, in case you would be able to inspect this specific point in time with a certain tool. (idk maybe I'm going insane) Had to close it