# error after yarn dev
## What happened
Issue e2b-dev/e2b#3 (closed, 12 comments): Hey guys, first of all thank you for the work. I´ve tried it out but i´m getting some errors after starting everything with yarn dev: When i´m trying to login i´ll get the message: Failed to fetch ``` yarn run v1.22.19 $ npx concurrently -p none "next dev" "yarn start:api" "yarn start:playground" $ cd api-service && QUART_APP=app:app PYTHONUNBUFFERED=1 poetry run quart --debug run --reload --port 49155 $ cd api-service/playground && yarn dev $ concurrently "nodemon -q" "nodemon --config nodemon-tsoa.json " ready - started server on the all-interfaces address:3000, url: YOUR_HOST info - Loaded env fro
## What works
Switch poetry to the right interpreter with the full path: `poetry env use /full/path/to/python` (`poetry env use $(which python)` works if python is on your PATH).
## Caveats
This comes from one real issue thread (gh:e2b-dev/e2b#3); it is the verified fix or approach from that thread, not a general manual. Check your version of E2B first , maintainers often fix the underlying bug in a later release, and the thread may predate it.