Question posted in 
I was editing an open source Flask app – it was working just fine. I changed 1 thing in .scss file and the entire application fails to load.
I undid all the changes but nothing changes. I can no longer start my application.
Every time I run honcho start -f Local and navigate to localhost:5000/
I get this error webassets.exceptions.FilterError: Program file not found: sass
Here is a copy of the trace on my terminal
(venv) pcowe@Pauls-MacBook-Pro maps4all % honcho start -f Local
22:33:06 system | web.1 started (pid=71020)
22:33:06 system | redis.1 started (pid=71019)
22:33:06 system | worker.1 started (pid=71021)
22:33:06 redis.1 | 71019:C 12 Aug 2020 22:33:06.639 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
22:33:06 redis.1 | 71019:C 12 Aug 2020 22:33:06.639 # Redis version=6.0.1, bits=64, commit=00000000, modified=0, pid=71019, just started
22:33:06 redis.1 | 71019:C 12 Aug 2020 22:33:06.639 # Warning: no config file specified, using the default config. In order to specify a config file use redis-server /path/to/redis.conf
22:33:06 redis.1 | 71019:M 12 Aug 2020 22:33:06.640 * Increased maximum number of open files to 10032 (it was originally set to 2560).
22:33:06 redis.1 | 71019:M 12 Aug 2020 22:33:06.642 * Running mode=standalone, port=6379.
22:33:06 redis.1 | 71019:M 12 Aug 2020 22:33:06.642 # Server initialized
22:33:06 redis.1 | 71019:M 12 Aug 2020 22:33:06.643 * Loading RDB produced by version 6.0.1
22:33:06 redis.1 | 71019:M 12 Aug 2020 22:33:06.643 * RDB age 51 seconds
22:33:06 redis.1 | 71019:M 12 Aug 2020 22:33:06.643 * RDB memory usage when created 1.02 Mb
22:33:06 redis.1 | 71019:M 12 Aug 2020 22:33:06.643 * DB loaded from disk: 0.001 seconds
22:33:06 redis.1 | 71019:M 12 Aug 2020 22:33:06.644 * Ready to accept connections
22:33:07 worker.1 | /Users/pcowe/Desktop/maps4all/app/__init__.py:18: FlaskWTFDeprecationWarning: "flask_wtf.CsrfProtect" has been renamed to "CSRFProtect" and will be removed in 1.0.
22:33:07 web.1 | /Users/pcowe/Desktop/maps4all/app/__init__.py:18: FlaskWTFDeprecationWarning: "flask_wtf.CsrfProtect" has been renamed to "CSRFProtect" and will be removed in 1.0.
22:33:07 worker.1 | csrf = CsrfProtect()
22:33:07 web.1 | csrf = CsrfProtect()
22:33:07 web.1 | Importing environment from .env file
22:33:07 worker.1 | Importing environment from .env file
22:33:07 web.1 | /Users/pcowe/Desktop/maps4all/venv/lib/python3.7/site-packages/flask_sqlalchemy/__init__.py:835: FSADeprecationWarning: SQLALCHEMY_TRACK_MODIFICATIONS adds significant overhead and will be disabled by default in the future. Set it to True or False to suppress this warning.
22:33:07 worker.1 | /Users/pcowe/Desktop/maps4all/venv/lib/python3.7/site-packages/flask_sqlalchemy/__init__.py:835: FSADeprecationWarning: SQLALCHEMY_TRACK_MODIFICATIONS adds significant overhead and will be disabled by default in the future. Set it to True or False to suppress this warning.
22:33:07 web.1 | 'SQLALCHEMY_TRACK_MODIFICATIONS adds significant overhead and '
22:33:07 worker.1 | 'SQLALCHEMY_TRACK_MODIFICATIONS adds significant overhead and '
22:33:07 web.1 | * Serving Flask app "app" (lazy loading)
22:33:07 web.1 | * Environment: production
22:33:07 web.1 | WARNING: This is a development server. Do not use it in a production deployment.
22:33:07 web.1 | Use a production WSGI server instead.
22:33:07 web.1 | * Debug mode: on
22:33:07 worker.1 | 22:33:07 Worker rq:worker:99d42a58c1404444877927353f16c549: started, version 1.3.0
22:33:07 worker.1 | 22:33:07 *** Listening on default...
22:33:07 web.1 | * Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)
22:33:07 web.1 | * Restarting with stat
22:33:08 web.1 | /Users/pcowe/Desktop/maps4all/app/__init__.py:18: FlaskWTFDeprecationWarning: "flask_wtf.CsrfProtect" has been renamed to "CSRFProtect" and will be removed in 1.0.
22:33:08 web.1 | csrf = CsrfProtect()
22:33:08 web.1 | /Users/pcowe/Desktop/maps4all/venv/lib/python3.7/site-packages/flask_sqlalchemy/__init__.py:835: FSADeprecationWarning: SQLALCHEMY_TRACK_MODIFICATIONS adds significant overhead and will be disabled by default in the future. Set it to True or False to suppress this warning.
22:33:08 web.1 | 'SQLALCHEMY_TRACK_MODIFICATIONS adds significant overhead and '
22:33:08 web.1 | * Debugger is active!
22:33:08 web.1 | * Debugger PIN: 314-175-405
22:33:45 web.1 | 127.0.0.1 - - [12/Aug/2020 22:33:45] "GET / HTTP/1.1" 500 -
22:33:45 web.1 | Traceback (most recent call last):
22:33:45 web.1 | File "/Users/pcowe/Desktop/maps4all/venv/lib/python3.7/site-packages/webassets/filter/__init__.py", line 518, in subprocess
22:33:45 web.1 | shell=os.name == 'nt')
22:33:45 web.1 | File "/Users/pcowe/opt/anaconda3/lib/python3.7/subprocess.py", line 775, in __init__
22:33:45 web.1 | restore_signals, start_new_session)
22:33:45 web.1 | File "/Users/pcowe/opt/anaconda3/lib/python3.7/subprocess.py", line 1522, in _execute_child
22:33:45 web.1 | raise child_exception_type(errno_num, err_msg, err_filename)
22:33:45 web.1 | FileNotFoundError: [Errno 2] No such file or directory: 'sass': 'sass'
22:33:45 web.1 |
22:33:45 web.1 | During handling of the above exception, another exception occurred:
22:33:45 web.1 |
22:33:45 web.1 | Traceback (most recent call last):
22:33:45 web.1 | File "/Users/pcowe/Desktop/maps4all/venv/lib/python3.7/site-packages/flask/app.py", line 2464, in __call__
22:33:45 web.1 | return self.wsgi_app(environ, start_response)
22:33:45 web.1 | File "/Users/pcowe/Desktop/maps4all/venv/lib/python3.7/site-packages/flask/app.py", line 2450, in wsgi_app
22:33:45 web.1 | response = self.handle_exception(e)
22:33:45 web.1 | File "/Users/pcowe/Desktop/maps4all/venv/lib/python3.7/site-packages/flask/app.py", line 1867, in handle_exception
22:33:45 web.1 | reraise(exc_type, exc_value, tb)
22:33:45 web.1 | File "/Users/pcowe/Desktop/maps4all/venv/lib/python3.7/site-packages/flask/_compat.py", line 39, in reraise
22:33:45 web.1 | raise value
22:33:45 web.1 | File "/Users/pcowe/Desktop/maps4all/venv/lib/python3.7/site-packages/flask/app.py", line 2447, in wsgi_app
22:33:45 web.1 | response = self.full_dispatch_request()
22:33:45 web.1 | File "/Users/pcowe/Desktop/maps4all/venv/lib/python3.7/site-packages/flask/app.py", line 1952, in full_dispatch_request
22:33:45 web.1 | rv = self.handle_user_exception(e)
22:33:45 web.1 | File "/Users/pcowe/Desktop/maps4all/venv/lib/python3.7/site-packages/flask/app.py", line 1821, in handle_user_exception
22:33:45 web.1 | reraise(exc_type, exc_value, tb)
22:33:45 web.1 | File "/Users/pcowe/Desktop/maps4all/venv/lib/python3.7/site-packages/flask/_compat.py", line 39, in reraise
22:33:45 web.1 | raise value
22:33:45 web.1 | File "/Users/pcowe/Desktop/maps4all/venv/lib/python3.7/site-packages/flask/app.py", line 1950, in full_dispatch_request
22:33:45 web.1 | rv = self.dispatch_request()
22:33:45 web.1 | File "/Users/pcowe/Desktop/maps4all/venv/lib/python3.7/site-packages/flask/app.py", line 1936, in dispatch_request
22:33:45 web.1 | return self.view_functions[rule.endpoint](**req.view_args)
22:33:45 web.1 | File "/Users/pcowe/Desktop/maps4all/app/main/views.py", line 68, in index
22:33:45 web.1 | modal=modal_attributes))
22:33:45 web.1 | File "/Users/pcowe/Desktop/maps4all/venv/lib/python3.7/site-packages/flask/templating.py", line 140, in render_template
22:33:45 web.1 | ctx.app,
22:33:45 web.1 | File "/Users/pcowe/Desktop/maps4all/venv/lib/python3.7/site-packages/flask/templating.py", line 120, in _render
22:33:45 web.1 | rv = template.render(context)
22:33:45 web.1 | File "/Users/pcowe/Desktop/maps4all/venv/lib/python3.7/site-packages/jinja2/environment.py", line 1090, in render
22:33:45 web.1 | self.environment.handle_exception()
22:33:45 web.1 | File "/Users/pcowe/Desktop/maps4all/venv/lib/python3.7/site-packages/jinja2/environment.py", line 832, in handle_exception
22:33:45 web.1 | reraise(*rewrite_traceback_stack(source=source))
22:33:45 web.1 | File "/Users/pcowe/Desktop/maps4all/venv/lib/python3.7/site-packages/jinja2/_compat.py", line 28, in reraise
22:33:45 web.1 | raise value.with_traceback(tb)
22:33:45 web.1 | File "/Users/pcowe/Desktop/maps4all/app/templates/main/index.html", line 1, in top-level template code
22:33:45 web.1 | {% extends 'layouts/base.html' %}
22:33:45 web.1 | File "/Users/pcowe/Desktop/maps4all/app/templates/layouts/base.html", line 5, in top-level template code
22:33:45 web.1 | {% include 'partials/_head.html' %}
22:33:45 web.1 | File "/Users/pcowe/Desktop/maps4all/app/templates/partials/_head.html", line 8, in top-level template code
22:33:45 web.1 | {% assets 'app_css' %}<link rel="stylesheet" type="text/css" href="{{ ASSET_URL }}">{% endassets %}
22:33:45 web.1 | File "/Users/pcowe/Desktop/maps4all/venv/lib/python3.7/site-packages/webassets/ext/jinja2.py", line 187, in _render_assets
22:33:45 web.1 | urls = bundle.urls(calculate_sri=True)
22:33:45 web.1 | File "/Users/pcowe/Desktop/maps4all/venv/lib/python3.7/site-packages/webassets/bundle.py", line 833, in urls
22:33:45 web.1 | urls.extend(bundle._urls(new_ctx, extra_filters, *args, **kwargs))
22:33:45 web.1 | File "/Users/pcowe/Desktop/maps4all/venv/lib/python3.7/site-packages/webassets/bundle.py", line 768, in _urls
22:33:45 web.1 | *args, **kwargs)
22:33:45 web.1 | File "/Users/pcowe/Desktop/maps4all/venv/lib/python3.7/site-packages/webassets/bundle.py", line 620, in _build
22:33:45 web.1 | force, disable_cache=disable_cache, extra_filters=extra_filters)
22:33:45 web.1 | File "/Users/pcowe/Desktop/maps4all/venv/lib/python3.7/site-packages/webassets/bundle.py", line 544, in _merge_and_apply
22:33:45 web.1 | kwargs=item_data)
22:33:45 web.1 | File "/Users/pcowe/Desktop/maps4all/venv/lib/python3.7/site-packages/webassets/merge.py", line 280, in apply
22:33:45 web.1 | return self._wrap_cache(key, func)
22:33:45 web.1 | File "/Users/pcowe/Desktop/maps4all/venv/lib/python3.7/site-packages/webassets/merge.py", line 222, in _wrap_cache
22:33:45 web.1 | content = func().getvalue()
22:33:45 web.1 | File "/Users/pcowe/Desktop/maps4all/venv/lib/python3.7/site-packages/webassets/merge.py", line 255, in func
22:33:45 web.1 | getattr(filter, type)(data, out, **kwargs_final)
22:33:45 web.1 | File "/Users/pcowe/Desktop/maps4all/venv/lib/python3.7/site-packages/webassets/filter/sass.py", line 148, in input
22:33:45 web.1 | self._apply_sass(_in, out, os.path.dirname(source_path))
22:33:45 web.1 | File "/Users/pcowe/Desktop/maps4all/venv/lib/python3.7/site-packages/webassets/filter/sass.py", line 142, in _apply_sass
22:33:45 web.1 | return self.subprocess(args, out, _in, cwd=child_cwd)
22:33:45 web.1 | File "/Users/pcowe/Desktop/maps4all/venv/lib/python3.7/site-packages/webassets/filter/__init__.py", line 520, in subprocess
22:33:45 web.1 | raise FilterError('Program file not found: %s.' % argv[0])
22:33:45 web.1 | webassets.exceptions.FilterError: Program file not found: sass.
22:33:45 web.1 | 127.0.0.1 - - [12/Aug/2020 22:33:45] "GET /?__debugger__=yes&cmd=resource&f=style.css HTTP/1.1" 200 -
22:33:45 web.1 | 127.0.0.1 - - [12/Aug/2020 22:33:45] "GET /?__debugger__=yes&cmd=resource&f=jquery.js HTTP/1.1" 200 -
22:33:45 web.1 | 127.0.0.1 - - [12/Aug/2020 22:33:45] "GET /?__debugger__=yes&cmd=resource&f=debugger.js HTTP/1.1" 200 -
22:33:45 web.1 | 127.0.0.1 - - [12/Aug/2020 22:33:45] "GET /?__debugger__=yes&cmd=resource&f=console.png HTTP/1.1" 200 -
22:33:45 web.1 | 127.0.0.1 - - [12/Aug/2020 22:33:45] "GET /?__debugger__=yes&cmd=resource&f=ubuntu.ttf HTTP/1.1" 200 -
Please help, how can I resolve this?
2
Answers
Rerun app.
I’m writing this 7 months after your initial question, so I doubt you still need an answer; Looks like you need to install SASS. If I forget to install LESSC on a new machine, I get something similar in my own project.
It is also possible that the code you use to create assets is optional for a production environment (which this looks like). In that case, you may need to copy up the assets and comment out the calling code.