To enjoy the latest features available on Chromecast, your device might need to update to the most recent software version. The update is done automatically as part of the setup, so you don't need to do anything.
If you have a Chromecast with Google TV, the update doesn't appear in the Google Home app. You need to access your Chromecast updates from your TV. To do this on your Chromecast with Google TV home screen, choose Settings 
Note: During the update, Chromecast isn't available to cast. Wait until the update is complete to try to cast.
Here's an overview of what you should expect during the update:
- Your Google Home app provides indication of the setup progress.
- You can check the status of your update on the TV.
- You can use the LED on the side of the Chromecast to verify that it still receives the update.
- The update typically takes up to 10 minutes. If the update takes much longer than expected, check the LED status to verify the device is still updating. The Chromecast should pulse red while it receives the update.
- If needed, you can reboot the Chromecast to automatically restart the update. Unplug your device from the power source and then wait for one minute before you plug it back in.
If the issue persists, factory reset the device and try to set it up again, preferably on a 2.4 GHz network, if available.