Nest is now rolling out a 4.0.1 upgrade to its smart thermostat after last month’s faulty 4.0 firmware caused Wi-Fi and battery issues. Update 1/7/14: Nest tells me the 4.0 bugs are not responsible for turning people’s heat off or down in the dead of winter, but that Nest hardware issues are sometimes to blame. Other causes include incompatible furnaces and people forgetting to change their air filters.]

This in part explains what’s going on if if you check out Nest’s Facebook wall or run a Twitter search on it.

@nest Coldest night in Iowa in years, and I wake up at 4 AM with the temp. dropped to 54 degrees, and the Nest is cycling on/off constantly. — Richard Harms (@richharms) January 6, 2014

Customers like Clayton and Richard (seen above) have been flocking to social media to report Nest problems ranging from annoyance to disaster. Some say they’ve come home or woken up in the middle of the night to a freezing cold house. When they investigate their Nest, they find it turning on and off repeatedly, or suddenly out of battery. In some cases it’s shut off or down their heat. One unlucky customer had his pipes freeze because his house got so cold.

One user wrote to TechCrunch explaining his Nest issues in detail:

“At about 4PM Friday, our heat shut off without warning. On inspection, the Nest unit appeared to be stuck in an endless loop of power cycling. Each time it powered on, it would display the spinning blue loading indicator, and then a message would appear, instructing that we detach the Nest from the mount and reattach it. After being reattached, the unit displayed a message indicating that it was restarting, and the process would repeat indefinitely. We followed the online troubleshooting guide with no success. We then tried to call support, but were met with impressively-long wait-times and a message acknowledging the existence of a breaking software change that seems to have been pushed out just as the bulk of the country was starting to rely on their furnaces.”

[Update 1/7/14:

Originally after speaking to Nest, I got the impression that the company felt that incompatibility, clogged air filters, and other problems beyond its control were solely responsible for people losing heat. That’s why I published with the headline “Nest Says Shut-Off Heat Not Its Fault, But Pushes Thermostat Update To Fix 4.0 Problems”. But after speaking to a representative today, the company clarified that in some cases Nest inaccurately tells customers they don’t need a common wire to power their Nest thermostat when they do. The lack of a needed common wire can cause Nest to malfunction and shut off or lower a home’s heat. Some users have mistakenly blamed this issue on the faulty 4.0 update when in fact it’s unrelated. It’s good to see Nest now being more clear about taking responsibility for issues that seriously affect customers.]

While there are plenty of happy customers who’ve had no problems, others are angry Nest didn’t proactively notify users about the 4.0 bugs. Instead, last month Nest posted to its support center about “Intermittent low battery or connectivity issues with thermostat software 4.0”. There it says:

“We have discovered a bug in our latest 4.0 thermostat software that affects a small percentage of our users…affected users will see a low battery warning on the thermostat, see their thermostat as “OFFLINE” intermittently in the app, and won’t be able to control them using the Nest app….As of Sunday, Dec. 8th, we have a short-term solution and have started updating affected thermostats. We’re rolling these thermostats back to version 3.5.3, which should fix the problem.”

Unfortunately, some people rolled back to 3.5.3 are experiencing a new set of issues. Exacerbated by lots of new users installing Nest products they received for Christmas, customers contacting support are enduring extremely long wait times. Those who do get help on the phone or over email are given long sets of instructions to troubleshoot their own devices.

Affected customers are demanding Nest do more thorough testing of its updates before pushing them out, or at least provide a way to turn off automatic updates. In the meantime, some are switching back to their old, cheap analog thermostats.

But today, I spoke with Nest co-founder Matt Rogers who says the 4.0.1 update is ready and is now being rolled out. He also denied that Nest issues shut off people’s heat. In a statement, the company explains:

“As stated in the support center message, the 4.0 update caused a small percentage of customers to lose Wi-Fi connectivity and therefore the ability to control the temperature remotely. Their heating and cooling remains unaffected except for remote control. We’ve rolled many of those customers back to 3.5.3 to resolve Wi-Fi connectivity while we work on the fix. In the coming days, we expect to release version 4.0.1, which has the same Wi-Fi performance as 3.5.3 with all the great features of version 4.0. Regarding the small percentage of customers who experience drained batteries, we work with users who contact our Support team on a case-by-case basis because there are many variables that can cause this – including homes with clogged air filters, or with old or unusual HVAC wiring. Sometimes the fix is to run a power wire, other times the customer’s system is incompatible with Nest. To clarify, this is not related to the 4.0 update. “

It seems anyone with problems or considering buying a Nest should be sure to change their air filters and ensure their furnace is compatible.

Still, Nest will need to better educate customers and ramp up support to avoid being blamed for problems it didn’t cause. Otherwise, customer issues like these could shake confidence in Nest right as Re/code reports it’s trying to raise $150 million to $200 million at a $2 billion to $3 billion valuation. Fortune’s Dan Primack says this round “remains very much a work in progress.”

That work could get a lot harder if investors worry Nest is souring opinions of some of its earliest adopters, even if it’s not responsible for problems. Because accurate or not, people’s opinions on social media influence their friends’ buying habits.

Every product has its vocal minority of jilted users and we can’t verify that all the issues customers are reporting are entirely Nest’s fault. But there seems to be a critical mass of discontent right now. For what it’s worth, though, Rogers sounded legitimately saddened about the 4.0 problems distressing customers, and told me “We do take these things really seriously, even if it’s not our fault. We’ll answer support calls and we’re always there to help people when they have issues.”

As we move toward having more of our lives managed by high-tech devices, their creators will need to double down on stability and security. Unlike work or entertainment gadgets, devices like Nest’s thermostats and smoke detectors are vital pieces of home infrastructure. Software bugs don’t just cause inconveniences, but real quality-of-life and safety issues. “Move fast and break things” just doesn’t work when you’re involved in our survival.