A report in the technology website TechCrunch said the company had confirmed the outage, but had given no information about what had caused it or how many customers were affected.
Users of the Chromecast Product Forum noticed the outage early on Wednesday morning (US time) when the Chromecast icon disappeared from streaming applications like Netflix, HBO and YouTube.
On social media, some users speculated that Chromecast devices had been affected by a software update. Google did not either confirm or deny this.
One user, Don Nguyen, wrote in the Google Home forum: "All three of my Google Home Minis stopped working this morning. I rebooted and reset... Tried setting them up again. All are completely worthless now."
TechCrunch said it had confirmed the issues, by testing out its own Google Home Mini.
"Saying 'Hey Google' will have the device immediately answer 'there was a glitch, try again in a few seconds' or 'sorry, something went wrong, try again in a few seconds'," the site's Sarah Perez wrote.
Contacted for comment, a Google spokesperson said: "We're aware of an issue affecting some Google Home and Chromecast users. We’re investigating the issue and working on a solution.".
Update, 9.40am AEST: A Google spokesperson contacted iTWire with the following message: "We’ve identified a fix for the issue impacting Google Home and Chromecast users and it will be automatically rolled out over the next six hours.
"If you would like an immediate fix please follow the directions to reboot your device. If you're still experiencing an issue after rebooting, contact us at Google Home Support. We are really sorry for the inconvenience and are taking steps to prevent this issue from happening in the future."