Plugin is not working on Ubuntu Vi IMproved 8.0 about simpylfold HOT 3 OPEN

Without having an Ubuntu machine on hand, it's difficult to know what to suggest.

foldexpr is set in the ftplugin scripts, which depend on Vim detecting your file type as python or cython. If your configuration on Ubuntu results in a different detected filetype, then it won't be set properly.

Try running :scriptnames after opening a Python file and see whether SimpylFold scripts appear in the list.

If foldexpr is being set correctly by SimpylFold but then is later overridden with a 0 by some other script, then :verbose set foldexpr? should reveal the location where it was last set.

Finally, maybe it's obvious, but your Vim has to be compiled with folding support for folding to work at all. Check the output of :version for +folding to see if the feature is enabled.

from simpylfold.

Thank you for the hints.

:set filetype? returns:
filetype=python

:scriptnames returns:
1: /usr/share/vim/vimrc
2: /usr/share/vim/vim81/debian.vim
3: /usr/share/vim/vim81/syntax/syntax.vim
4: /usr/share/vim/vim81/syntax/synload.vim
5: /usr/share/vim/vim81/syntax/syncolor.vim
6: /usr/share/vim/vim81/filetype.vim
7: ~/.vim/vimrc
8: /usr/share/vim/vim81/syntax/nosyntax.vim
9: /usr/share/vim/vim81/plugin/getscriptPlugin.vim
10: /usr/share/vim/vim81/plugin/gzip.vim
11: /usr/share/vim/vim81/plugin/logiPat.vim
12: /usr/share/vim/vim81/plugin/manpager.vim
13: /usr/share/vim/vim81/plugin/matchparen.vim
14: /usr/share/vim/vim81/plugin/netrwPlugin.vim
15: /usr/share/vim/vim81/plugin/rrhelper.vim
16: /usr/share/vim/vim81/plugin/spellfile.vim
17: /usr/share/vim/vim81/plugin/tarPlugin.vim
18: /usr/share/vim/vim81/plugin/tohtml.vim
19: /usr/share/vim/vim81/plugin/vimballPlugin.vim
20: /usr/share/vim/vim81/plugin/zipPlugin.vim
21: ~/.vim/pack/plugins/start/SimpylFold/plugin/SimpylFold.vim
22: /usr/share/vim/vim81/syntax/python.vim

SimpylFold is loaded on line 21

:verbose set foldexpr? returns:
foldexpr=0

My vim supports folding

But Simpylfold is still not working. Once I try to fold I get this error:
E490: No fold found

:version
VIM - Vi IMproved 8.1 (2018 May 18, compiled Sep 20 2021 11:42:42)
Included patches: 1-2269
Modified by [email protected]
Compiled by [email protected]
Huge version without GUI. Features included (+) or not (-):
+acl +cindent +cursorshape +file_in_path +jumplist +mksession +mouse_xterm +printer +sound +terminal +virtualedit -xim
+arabic -clientserver +dialog_con +find_in_path +keymap +modify_fname +multi_byte +profile +spell +terminfo +visual -xpm
+autocmd -clipboard +diff +float +lambda +mouse +multi_lang -python +startuptime +termresponse +visualextra -xsmp
+autochdir +cmdline_compl +digraphs +folding +langmap -mouseshape -mzscheme +python3 +statusline +textobjects +viminfo -xterm_clipboard
-autoservername +cmdline_hist -dnd -footer +libcall +mouse_dec +netbeans_intg +quickfix -sun_workshop +textprop +vreplace -xterm_save
-balloon_eval +cmdline_info -ebcdic +fork() +linebreak +mouse_gpm +num64 +reltime +syntax +timers +wildignore
+balloon_eval_term +comments +emacs_tags +gettext +lispindent -mouse_jsbterm +packages +rightleft +tag_binary +title +wildmenu
-browse +conceal +eval -hangul_input +listcmds +mouse_netterm +path_extra -ruby -tag_old_static -toolbar +windows
++builtin_terms +cryptv +ex_extra +iconv +localmap +mouse_sgr -perl +scrollbind -tag_any_white +user_commands +writebackup
+byte_offset +cscope +extra_search +insert_expand -lua -mouse_sysmouse +persistent_undo +signs -tcl +vartabs -X11
+channel +cursorbind -farsi +job +menu +mouse_urxvt +postscript +smartindent +termguicolors +vertsplit -xfontset

from simpylfold.

Your Vim doesn't seem to be loading the ftplugin script (ftplugin/python/SimpylFold.vim), which is what sets foldexpr to the correct value for SimpylFold. You may have turned ftplugins off, or maybe the default configuration on Ubuntu is doing so. Try :filetype plugin on (or put that in your .vimrc) and then load/reload a Python buffer.

from simpylfold.