Error while formatting on save for python files

[theairbend3r]

Hi, I'm getting the following error while formatting a python file.

Error detected while processing BufWritePost Autocommands for "*.py":
E492: Not an editor command: FormatWrite
Error detected while processing BufWritePost Autocommands for "<buffer=1>":
E5108: Error executing lua [string ":lua"]:1: module 'lint' not found:
        no field package.preload['lint']
        no file './lint.lua'
        no file '/usr/share/luajit-2.1.0-beta3/lint.lua'
        no file '/usr/local/share/lua/5.1/lint.lua'
        no file '/usr/local/share/lua/5.1/lint/init.lua'
        no file '/usr/share/lua/5.1/lint.lua'
        no file '/usr/share/lua/5.1/lint/init.lua'
        no file '/home/akshaj/.cache/nvim/packer_hererocks/2.1.0-beta3/share/lua/5.1/lint.lua'
        no file '/home/akshaj/.cache/nvim/packer_hererocks/2.1.0-beta3/share/lua/5.1/lint/init.lua'
        no file '/home/akshaj/.cache/nvim/packer_hererocks/2.1.0-beta3/lib/luarocks/rocks-5.1/lint.lua'
        no file '/home/akshaj/.cache/nvim/packer_hererocks/2.1.0-beta3/lib/luarocks/rocks-5.1/lint/init.lua'
        no file './lint.so'
        no file '/usr/local/lib/lua/5.1/lint.so'
        no file '/usr/lib/x86_64-linux-gnu/lua/5.1/lint.so'
        no file '/usr/local/lib/lua/5.1/loadall.so'
        no file '/home/akshaj/.cache/nvim/packer_hererocks/2.1.0-beta3/lib/lua/5.1/lint.so'
stack traceback:
        [C]: in function 'require'
        [string ":lua"]:1: in main chunk

My null ls setup

local null_ls = require("null-ls")    
local formatting = null_ls.builtins.formatting    
local diagnostics = null_ls.builtins.diagnostics    
    
null_ls.setup({    
    sources = {                                                          
        formatting.black,                                   
        diagnostics.flake8,                                                                                                       
        formatting.prettier,                                                        
        diagnostics.eslint_d,                                      
        formatting.stylua,                                   
        formatting.latexindent,                                        
        formatting.trim_newlines,                                             
        formatting.trim_whitespace,                                    
    },                                                                                                 
    on_attach = function(client)                                                                             
        if client.resolved_capabilities.document_formatting then                                   
            vim.cmd([[                                   
            augroup LspFormatting                                   
                autocmd! * <buffer>                                   
                autocmd BufWritePre <buffer> lua vim.lsp.buf.formatting_sync()                                   
            augroup END                                              
            ]])                                   
        end                                         
    end,                                                     
})    

I am able to format my lua files properly so null_ls seems to be working. I'm not sure what the issue with .py file is. Is my config wrong?

[syphar]

It looks to me as if this is coming from another plugin. Null-LS runs on BufWritePre as you configured it, the error happens on BufWritePost.

[theairbend3r]

Oh yes! That's a great observation. It helped me sort it out. I had migrated from using formatter and nvim-lint to null.ls. Those two libraries had an autcommand that used BufWritePost. I deleted those lines and null.ls started working perfectly. Thank you! :)