Elpy-rpc in Emacs gives 'exited abnormally with code 1' error and unexpected output. How can I fix it?

emacs elpy-20230402.1946 started giving me strange errors relating to its elpy-rpc:

"error in process sentinel: elpy-rpc--default-error-callback: peculiar error: "exited abnormally with code 1"

And this cryptic error message:

Output from Backend

There was some unexpected output from the Elpy backend. This is

usually not a problem and should usually not be reported as a bug with

Elpy. You can safely hide this buffer and ignore it. You can also see

the output below in case there is an actual problem.

Output

[TerminalIPythonApp] WARNING | Unrecognized alias: 'W', it will have no effect.

[TerminalIPythonApp] CRITICAL | Bad config encountered during initialization: Error loading argument W=['ignore'], values whose keys begin with an uppercase char must be Config instances: 'W', DeferredConfigString('ignore')

It appears communication with elpy-rpc has broken down, and it constantly beeps whenever it is supposed to offer auto-complete suggestions, etc, elpy is now unusable for me as I cannot type a single word without it constantly complaining.

This error appeared out of nowhere after I upgraded emacs packages today (May 31, 2023). I also upgraded my conda base environment, but I don't know if that has anything to do with the problem or not, but my python and ipython executables installed with conda work just fine. The environment variables are set correctly. I have no idea even where to start with this sort of error.

Is there a way to fix this or maybe downgrade elpy until this problem is fixed?

I tried editing a python file and expected normal functioning of this emacs package. I can't think of anything that changed other than my usual emacs package upgrades and upgrade of conda environment.

Have you checked elpy issue 1729?
In particular the answer of Krisselack did the trick for me.

TL/DR

What worked for me:

• in emacs do a package-delete on elpy

• in the .emacs.d directory remove everything related to elpy

• restart emacs

• re-install elpy