Forms and slots error

Rasa Open Source
1

i use rasa ver 2.8.7 and get this error message, how to fix this?

The provided domain file could not be loaded. Error: The slots for form ‘form_crypto_price’ were specified as ‘<class ‘NoneType’>’. They need to be specified as dictionary. Please see Forms for more information.

slots:

crypto:

type: text

influence_conversation: true

stock:

type: text

influence_conversation: true

forms:

crypto_price_form:

required_slots:

  crypto:

  - type: from_text

form_stock_price:

required_slots:

  stock:

  - type: from_text