Hi, I have a similar error.
When try to install a Python with aapanel web (button INSTALL on the Python Manager module), a error occours:

Sorry, something went wrong:
Traceback (most recent call last):
File "class/flask_sockets.py", line 30, in call
handler, values = adapter.match()
File "/www/server/panel/pyenv/lib/python3.7/site-packages/werkzeug/routing.py", line 1945, in match
raise NotFound()
werkzeug.exceptions.NotFound: 404 Not Found: The requested URL was not found on the server. If you entered the URL manually please check your spelling and try again.
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "class/panelPlugin.py", line 1902, in a
return eval(execStr)
File "", line 1, in
File "plugin/pythonmamager/pythonmamager_main.py", line 706, in InstallPythonV
v = get.version
AttributeError: 'dict_obj' object has no attribute 'version'
I reinstall yhe Pyrhon manager and no results.
Also, I run the command (mi root directory /www):
1 retry:
/www/server/panel/pyenv/bin/pyenv install --list
-bash: /www/server/panel/pyenv/bin/pyenv: No such file or directory
2 retry:
/www/server/panel/pyenv/bin/pyvenv install --list
WARNING: the pyenv script is deprecated in favour of python3.7 -m venv
3r retry:
/www/server/panel/pyenv/bin/python install --list
/www/server/panel/pyenv/bin/python: can't find 'main' module in 'install'