You are recommended to close the Google Home app in the background and relink again with the latest Chrome browser(make sure your Google Home is latest version, download the latest Chrome and set as your default browser in you mobile phone). If it still fails, Please refer to the following information: Android users, please refer to steps 1, 2 and 3, and IOS users only refer to step 3.
1. Check if the Google Home app is updated to the latest version? To check, please visit Play Store. If this does not work, please try step 2.
2. Try clearing the cache and data of the Google App: Settings > Apps > Google Home App > Storage > Clear Cache and then tap on Manage Space > Clear All Data. Please note that this will delete all the preferences of the Google Home App including the widgets. If this does not work, please try step 3.
3. Submit feedback from the Google Home app with the keywords: "Smart We Link account won't link". Please make sure to check the box to include the logs and reports.