Something is broken in Garmin's firmware, and it has been broken for months.
Garmin released software version 27.09 for several Forerunner watches back in January 2026, and users have been reporting problems ever since. The issues are not minor - people are seeing completely wrong elevation data, broken heart rate tracking, GPS failures, and battery drain that turns their watches into bricks overnight.
What makes this worse is that Garmin has not acknowledged the problem publicly or released a fix.
What Owners Are Experiencing
The reports started appearing on Garmin's forums and Reddit shortly after the January update. Users with Forerunner 255, 265, 955, and 965 watches were all experiencing similar problems.
The most common complaint is elevation tracking going haywire. People are seeing notifications that they climbed dozens of floors while sitting at their desks. One user reported their watch showing 50 meters of elevation gain in 5 minutes while running on flat ground. The altimeter appears to be registering phantom climbs constantly, even when the watch is sitting motionless.
The elevation issue is particularly frustrating because Garmin uses barometric altitude for elevation data, which should be more accurate than GPS-derived altitude. When it goes wrong, it goes completely wrong - producing impossible numbers that bear no relation to reality.
For trail runners who depend on accurate elevation gain for pacing and training load calculations, this renders the watch nearly useless on hilly routes. If you are trying to train by feel based on elevation-adjusted pace, you are flying blind.
Heart rate tracking has also taken a hit. Some users report slow response to intensity changes during runs - the optical sensor seems to lag behind actual effort, making it useless for training zones. Others see the heart rate lock onto a single number and refuse to update for entire workouts.
This is dangerous for runners doing interval training. If your watch shows 130 bpm when you are actually at 170 bpm, you might push harder than you should during recovery intervals, undermining your training.
Heart rate tracking has also taken a hit. Some users report slow response to intensity changes during runs - the optical sensor seems to lag behind actual effort, making it useless for training zones. Others see the heart rate lock onto a single number and refuse to update for entire workouts.
GPS issues have surfaced too. Some users report the watch failing to acquire a signal at all after updating. Others see GPS lock but with wildly inaccurate pace and distance data.
GPS problems are particularly concerning because they affect the core function of a running watch. If your distance and pace are wrong, the watch is not just annoying - it is actively misleading you about your workout. One user reported their watch thinking they ran 15 miles when they had actually run 8.
The combination of GPS errors and elevation errors together means some users have completely unusable data from workouts they thought they were tracking properly.
Battery drain is the final complaint. Several users have watched their watch go from 86% battery to 9% overnight - a catastrophic drain that turns a multi-day battery life watch into something that needs charging twice a day.
For users who rely on their watch to track sleep and then wake them up, unexpected battery drain is particularly problematic. Imagine waking up to a dead watch and missing your morning alarm because the firmware decided to drain your battery overnight.
The battery issue also points to something being fundamentally wrong with how the firmware is managing the hardware. Excessive battery drain usually means a process is running constantly when it should be sleeping. Combined with the elevation and heart rate issues, it suggests the firmware is not properly managing any of the sensors.
The Human Cost
This is not just about numbers being wrong. For runners who use their watches for training decisions, bad data means bad decisions.
The Human Cost
This is not just about numbers being wrong. For runners who use their watches for training decisions, bad data means bad decisions.
If your watch thinks you climbed 30 floors during a workday when you actually sat at a desk, that data contaminates your training load calculations. If your heart rate zones are based on incorrect readings during a tempo run, you might be training harder or easier than you think.
One user on Garmin's forums described the situation as "insulting" - months of problems with no acknowledgment from Garmin. Another said they raised the issue with Garmin support and were sent a replacement watch, but suspected it was a software problem that the new hardware would also eventually develop.
What Garmin Is Saying
Nothing, essentially.
The company has not posted any acknowledgment of the firmware problems on their official channels. No workaround guide, no "we are aware of the issue," no timeline for a fix. The silence has frustrated users who feel they paid premium prices for watches that now do not work as advertised.
This is not how a company with Garmin's reputation should handle a widespread problem affecting multiple product lines. When Apple has a software problem, they acknowledge it and push a fix. When Garmin has a problem that affects core functionality for months, users get silence.
The lack of communication also makes it hard to recommend Garmin watches to new buyers. A watch that can be rendered nearly unusable by a software update is a hard sell.
The community consensus for users who have not yet updated to 27.09 is clear: disable automatic updates immediately. Once you install the problematic firmware, there is no way to downgrade to a stable version.
What You Can Do
If your Forerunner has not updated to 27.09 yet, do not let it update automatically. Go into Garmin Express or the Connect app and turn off automatic updates. This is the only way to guarantee you stay on stable firmware for now.
To disable automatic updates in Garmin Express, click on your device, then Software Update, and uncheck the automatic option. In the Connect app, go to your device settings and look for automatic update options there.
If you have already updated and are experiencing these problems, your options are limited. Contact Garmin support - some users have reported success getting replacement units. Do not expect a software fix anytime soon based on Garmin's track record of silence on this issue.
For now, the best advice is to be skeptical of your watch's data if you updated recently. Check your elevation, heart rate, and GPS data against your historical norms. If something looks wrong, it probably is. Keep notes of which workouts had obviously bad data in case you need to dispute results with Garmin support.
The Bigger Picture
Garmin has built its reputation on reliable, accurate fitness tracking. The Forerunner line is trusted by serious runners and athletes who depend on the data to guide their training. This kind of widespread, persistent bug undermines that trust.
Software bugs happen to every company. What matters is how they respond. Garmin's silence on this issue does not inspire confidence that it will be resolved quickly or transparently.
The longer this goes on, the more it damages Garmin's reputation for reliability. For a company that sells watches partly on the promise of accurate data, having that data be actively wrong for months is a serious problem.
If you are in the market for a new Garmin, this might be a reason to wait until the firmware situation stabilizes. Or at least, do not update until Garmin officially acknowledges and fixes the problem.
It is worth noting that Garmin has released newer firmware versions since 27.09 - the current version is 27.10 or higher on some models. However, users reporting problems say they are still experiencing issues even after updating to these newer versions. The problems may persist across firmware versions.
For the rest of us with Forerunner watches from 2022-2024, hold off on that update notification. Your watch is probably more reliable right now than it would be after installing 27.09.
We will continue monitoring this situation and update this article if Garmin releases a fix. If you are experiencing these issues, your best course of action is to contact Garmin support and document everything - screenshots, support ticket numbers, and notes about the problems you are seeing. The more data Garmin has from affected users, the better chance they eventually address this.
In the meantime, consider using your phone for GPS tracking as a backup until Garmin gets their firmware situation under control.