What Does This Error Mean?

Spotify failing to play on Google Nest is most often caused by the Spotify account being unlinked in the Google Home app, or both the phone and speaker not being on the same Wi-Fi network. In the Google Home app, go to Music > Spotify and re-link your account. Also ensure your phone and the Nest speaker are on the same Wi-Fi network.

Affected Models

Google Nest Mini
Google Nest Audio
Google Home
Google Home Mini
Google Nest Hub
Google Nest Hub Max

Common Causes

Spotify account unlinked from Google Home app
Phone on a different Wi-Fi network or data than the Nest speaker
Spotify app not updated — older versions have cast compatibility issues
Spotify Premium required for some Google Home voice command features
Google Home app needs update to fix Spotify integration

How to Fix It

Re-link Spotify in the Google Home app.

Open the Google Home app > Settings > Music. Find Spotify in the list and tap Link Account (or Re-link if already listed). Sign in to your Spotify account when prompted. This refreshes the OAuth connection between Google Home and Spotify.
Ensure phone and speaker are on the same Wi-Fi.

The Spotify app on your phone must be on the same Wi-Fi network as the Nest speaker to cast audio. Check that your phone is connected to Wi-Fi (not mobile data) and that it is the same network as the speaker. A guest network or separate SSID will prevent casting.
Set Spotify as the default music service.

In the Google Home app, go to Settings > Music > Default Music Service and select Spotify. When Spotify is set as default, saying 'Hey Google, play music' will use Spotify automatically. If another service is set as default, voice commands may not route to Spotify.
Update the Spotify app.

Open the App Store or Google Play and update Spotify to the latest version. Old Spotify versions have known issues with Google Cast that prevent audio from playing on Nest speakers. After updating, force-close Spotify and reopen it before testing.
Use the Spotify app Cast button directly.

In the Spotify app, tap the device icon (bottom of the Now Playing screen) and select your Nest speaker from the list. This casts directly from Spotify rather than going through Google Home. If this works but voice commands do not, the Google Home Spotify link needs refreshing.

When to Call a Professional

Spotify integration is a software and account issue — no hardware service is needed.