E21: Cannot make changes, 'modifiable' is off

[parthsharma1996]

When I try to go to the error(inconsistency with pep-8) in my code after running vim-flake8, by pressing enter.
E21: Cannot make changes, 'modifiable' is off
How do I resolve this?

[shollingsworth]

It has something to do with quickfix stealing focus.
I'm trying to solve the same problem :
EDIT:
The following solved this in ~/.vimrc

autocmd BufWritePost *.py call Flake8()
autocmd BufWritePost *.py wincmd p
autocmd BufWritePost *.py set ft=python