Invalid selector: Compound class names not permitted error using Selenium

As per the documentation of selenium.webdriver.common.by implementation:

class selenium.webdriver.common.by.By
    Set of supported locator strategies.

    CLASS_NAME = 'class name'

So,

• Using find_element_by_class_name() you won’t be able to pass multiple class names.
  Passing multiple classes you will face the error as:

  Message: invalid selector: Compound class names not permitted
  

• Additionally, as you want to return an array of the chats, so instead of find_element* you need to use find_elements*

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Solution

As an alternative you can use either of :the following Locator Strategies:

• CSS_SELECTOR:

  recived_msg = driver.find_elements_by_css_selector(".XELVh.selectable-text.invisible-space.copyable-text")
  

• XPATH:

  recived_msg = driver.find_elements_by_xpath("//*[@class="XELVh selectable-text invisible-space copyable-text"]")