Thanks, but I've tried them all (delete/reinstall, DNS change, different browser) on 3 separate networks and just using phone data. Still get the 404.
Tried a different Gmail account? You can create one in a few seconds if you don't have a secondary Gmail account and try using that to complete the process. Rules out a variable, at least. 
I'm sorry if this is a repeat answer but concerning the Google Home 404 error: I just found that it works properly on a Mobile Device that has Chrome as the default browser. I must have tried 30 times on my phone which has Firefox only. I switched to a phone which has Chrome only and things worked as they should. What a pain in the rump.
Gary
FYI - Firefox on Android/iOS has never been a supported browser for Hubitat. Here's the list of what is supported:
I assumed it was Google Home calling upon the default browser to finish the association, not Hubitat. In any case I was commenting that Google Home was the pain in the rump; certainly not Hubitat. I like Hubitat. I came from SmartThings.
I was finally able to authorize by doing two things (not sure which helped) - I changed DNS to Google's, but still got the 404 error. I simply hit the back button on my phone and got the authorization screen. Filled it out and voila!
TLDR:
Google Home authorization 404 errors continue to be a problem for me. Google is aware of the problem and is working on it.
Here are the details for the few who might care:
Thanks to many excellent suggestions from folks in this thread I've had the opportunity to learn about and attempt way too many ways to fix the problem with getting a 404 error when trying to get Hubitat authorization on Google Home (Android). I really want to be able to turn lights on in the dark by using my voice and set lighting scenes the same way.
Unfortunately absolutely none of the solutions worked for me, but it's very clear that they work for others. After much investigation @bobbyD said that it was clear that the problem was on the Google side and that I should follow up with them.
I started the process with Google on a Nov. 19th chat with tier 1 where I answered a lot of very detailed questions, That tier 1 chat continued and escalated to tier 2 where they asked even more questions. The whole chat went over an hour. Tier 2 originally estimated their investigation would take 24-48 hours but that didn't happen. They eventually sent a series of emails asking for more and more information like logs, screenshots, video of the process, and submitting feedback within the Google Home app that was tied to an authorization attempt and included the Google ticket number. It's now almost three weeks in and I got what I hope is a promising email just now that said:
"Thanks for reaching out to the Google Senior Support Team.
I hope you are doing well!
I just want to inform you that we are aware of this situation and our team is currently investigating it for a stable fix."
So, for those of us who want this to work there may be hope. I'll be sure to post "the end of the story".
Thanks for the status update. Always nice to figure things out and share with others. Hopefully you get to the bottom of this issue sooner rather than later.
Have you ever tried a different Google Account? I know I previously suggested this troubleshooting step. I’d really like to know if that solves the issue or not? Even if you have a friend with a different Google Account and Phone, it would be nice to know if the problems persists (I.e. an issue on the Hubitat side) or if everything ‘just works’ as it does for most of the rest of us (I.e. an issue with your particular Google account.)
TLDR: After 3½ weeks, countless 404s, and one “Session token expired” detour — Google Home is now fully linked and working perfectly. Pigs are flying.
The full story for anyone who faces this and wants a full roadmap:
Thanks again for the many excellent suggestions in this thread. I learned a ton and tried literally everything. None of the usual fixes (cache clears, reboots, DNS tricks, etc.) worked for me, but it was clear they do work for others.
@bobbyD confirmed the problem was on Google’s side and my case was escalated to Hubitat Engineering.
Google Senior Support (tier 2 and possibly higher) grilled me with a lot of requests for info and eventually responded with a comprehensive list of things to try, most of which I had already done, but perhaps not all at one time. Before executing their list, I thought I’d try my normal authorization process again to establish a new baseline. Much to my surprise (after about 100+ previous attempts) I got a different result. Instead of a 404 error I got “Session token is expired”. I suspect that Google had reset something that caused the change, but I don’t know that (I'll ask if they did but don't know if I'll get an answer).
My final steps to eliminate the “Session token is expired” were:
- Hubitat → Google Home app → gear → Disable (not delete)
- Google Home app → unlink Hubitat (but in my case it had never linked)
- Clear GH app cache + data → restart phone
- Hubitat → Reboot hub
- Hubitat → Google Home → gear → Enable
- Link again in Google Home app → success
All lights, scenes, and remotes now respond flawlessly to voice commands.
Moral of the story: when Hubitat says “it’s on Google’s side”, believe them.
Thanks again to everyone who helped along the way. And yes, the pigs are officially airborne.
Google Senior Support’s full troubleshooting list (for reference):
• In the Hubitat admin interface: remove the Google Home integration.
• In the Google Home app: unlink or remove Hubitat (if present).
• Reboot the Hubitat hub (from its web settings page), this helps make sure its cloud registration resets.
• Clear cache and data from the Google Home app on the phone. Then restart the phone.
• On Hubitat: re‑enable the Google Home integration (built‑in), do not use any community or custom integration for now.
• In Google Home, start the “Works with Google” → add service → select Hubitat. Sign in, select the correct hub, and authorize the devices.
• If the 404 error persists: confirm the hub currently has a stable cloud connection. An unstable or mis‑registered cloud link often causes the “not found” error.
• If possible, try linking from a different network (e.g. mobile data or other Wi‑Fi) to rule out any router/NAT or firewall issue affecting cloud access.
Thank you for the update and for your persistence in resolving this. We are always careful not to blame external services unless the evidence is clear, as we never want to deflect responsibility. However, when an integration relies on a third-party platform, we are limited in what we can control.
Your write-up is a perfect example of why we try to be transparent about where the issue actually lives. If the problem is on our end, we own it and address it. If it lies with an external platform, standard troubleshooting steps—like reboots or reinstallations—won't resolve the core issue.
Thanks for taking the time to dig in and get to the bottom of it. 
Any idea on what to do if this doesn't work? I've tried everything I know to do. Found this thread and was convinced this would solve it. I've tried the final steps list several times and I still have the same issue/error. I just don't know what else to try. We just have a few google speakers in home, so it's not a crazy setup.
app:25302026-01-04 12:16:41.292
error
syncResponse Error: {
"error": {
"code": 404,
"message": "Requested entity was not found.",
"status": "NOT_FOUND"
}
}
, giving up for now
app:25302026-01-04 12:16:31.271
error
syncResponse Error: {
"error": {
"code": 404,
"message": "Requested entity was not found.",
"status": "NOT_FOUND"
}
}
, giving up for now
app:25302026-01-04 12:16:02.713
warn
unknownError: java.lang.IllegalArgumentException: Text must not be null or empty
app:25302026-01-04 12:15:59.313
info
updated...
app:25302026-01-04 12:15:38.602
error
syncResponse Error: {
What is your default browser on your phone?
Well, in that case I don't have any magic solution beyond all of the suggestions that have been posted in this thread, sorry.
I had been using Firefox on Android as my default browser and I discovered that absolutely caused 404 errors. When I made Chrome the default, then authorization would complete. When I switched back to Firefox I got the 404 error again. I've repeated this back and forth several times and at least for me the relationship between Firefox and 404 errors is absolute.
I appreciate everything you've done up to this point. It gave some additional things to try. I was so sure it was going to help/fix it, but I guess something else is happening. You mentioned at one point that you suspected google had to reset something on their side. Did you ever figure out if they did that? I don't know what it would be, but it appears that something is hanging somewhere despite being removed and re-added.
I tried to find out what they did but I got a 'non-response response. Their reply was essentially:
The engineers don’t share specific details with support — they just confirm the issue is being investigated/fixed on their side.
I spent an hour and 45 minutes on the phone with google. Most of that was tier 1 telling me I didn't need to sync hubitat and needed to sync the native apps for each device brand. I finally got to tier 2/senior and they didn't care at all. They told me hubitat was the issue and I needed to contact hubitat support. google said they couldn't do anything. I'm just stuck with it not working.
I went through the same frustration as you and if you have the time I'd really suggest you stick with it. I really struggled to get "Hey Google' to work but in the end all of the effort was totally worth it. With scenes, timers, and Hey Google I almost never touch a switch. Voice commands were absolutely the icing on the cake.
I have 52 lighting automation voice commands to cover a very wide variety of situations. My absolute favorite is a morning thing. When I'm ready to leave the bedroom and go to the kitchen I say "Hey Google, Bedroom Kitchen". The bedroom lights turn off and the kitchen lights turn on to a preferred brightness.
I hope you're able to stick with it and that you get it working.
It's finally fixed. I think I had two issues at once, but it came down to a rogue lutron fan control switch. I agree with you...going without the voice commands for the last few days has been almost crippling to our routines. We didn't realize how little we touch the switches until it hasn't been there.
I detailed it out on my original post in case anyone else ever has to deal with the same issue. C-8 Pro can't connect to Google Home - #7 by jaredeaves
Thanks for your help and encouragement to stick with it! I was about to do what the error kept saying....giving up for now...