Garmin Forerunner owners are raising fresh concerns online after a recent software update, with complaints centering on two of the most important metrics for training: heart rate accuracy and elevation data.
According to multiple user reports, the issues are being seen on several popular Garmin running watches, including the Forerunner 255, Forerunner 265, Forerunner 955, and Forerunner 965. The common thread appears to be software version 27.09, which some users say triggered problems that have persisted for months.
The most serious complaint involves unreliable heart rate tracking. For runners, cyclists, and other endurance athletes, heart rate isn’t just another number on the screen—it’s a core training signal used to measure effort, manage pacing, and stay in the right intensity zone. When distance tracking is off, athletes can often correct it later by adjusting a route. Heart rate data, however, is much harder to “fix” after a workout, and inaccurate readings can affect training decisions and long-term progress.
Alongside heart rate concerns, some users are also reporting incorrect elevation tracking. In at least one detailed account, workouts completed on flat ground were recorded as if they included major climbs, inflating elevation gain totals. For athletes who train with hill targets or track climbing metrics over time, elevation errors can be just as frustrating—especially when they suddenly appear after a firmware update.
Not everyone is experiencing the problems, and that makes it difficult to estimate how widespread the issue really is. While several comments echo similar experiences, others report their watches are working normally. Still, the consistency of model names and the repeated mention of version 27.09 has fueled criticism, particularly from users who believe the problems have been known since around January.
If you own a Garmin Forerunner 255, 265, 955, or 965 and you’ve noticed unusual heart rate spikes, inconsistent readings, or strangely high elevation gain on flat routes, you’re not alone. A practical next step is to report the issue directly to Garmin so support teams can log the case, confirm whether your device is affected, and potentially offer troubleshooting steps while attention on the problem grows.
For many athletes, a running watch is a training tool first and a smartwatch second. That’s exactly why accurate heart rate and elevation tracking matters—and why these Garmin Forerunner software update complaints are drawing so much attention right now.
