Forerunner 255 Series - Recent Threads

It wakes you up during sleep!

4057839 — Sat, 23 May 2026 11:45:06 GMT

I bought the Garmin Instinct 2X Solar almost exclusively for health tracking: sleep, heart rate, recovery, etc.

The watch itself has many great qualities, but one design decision is absolutely baffling:

It woke me up in the middle of the night by buzzing on my wrist to tell me that the battery was low.

Think about that for a second.

This is a device that actively tracks sleep, knows you are asleep, and still decides that the best possible moment to alert you about battery level is during the night while you are sleeping.

For a product marketed partly around health and sleep tracking, this is stupidity beyond redemtption.

Humans are building spacecraft and landing jeeps on Mars, yet somehow the people at Garmin thought:
“Maybe the sleep-tracking watch should wake people up during sleep because the battery has only two days left.”

This can probably be adjusted somewhere in Settings, but the default behavior is still completely ludicrous.

RE: It wakes you up during sleep!

Jacquers — Wed, 03 Jun 2026 09:40:44 GMT

Post in the Instinct 2 section of the forum, this one is for the 255, and reach out to support directly.

RE: June '26 updateupdate.

Jacquers — Wed, 03 Jun 2026 09:31:15 GMT

Probably GPS timezone info.

June '26 updateupdate.

chocorello — Wed, 03 Jun 2026 07:34:26 GMT

My FR255 wants to install an update since 31/5/26 or so. But it shows no info even through Garmin Express. I already have 27.09 installed so i cant imagine what is needed to be installed that is not mentioned in the forum, or the update process.

Any idea?

Wrong elevation gain in AUTO Sensor Mode – possible firmware 27.09 bug

gnardella — Sat, 25 Apr 2026 17:08:02 GMT

I've been running some tests on my Forerunner 255 after noticing an anomalous behavior in elevation gain calculation.

Setup:

Manual calibration performed
Barometer set to Sensor Mode: AUTO
The device was kept completely still throughout the entire observation

Theoretical background (from official manual)

According to the Garmin manual, AUTO mode uses both the altimeter and barometer based on detected movement. When stationary, barometric behavior is expected: pressure changes are treated as weather variations, elevation remains stable, and sea-level pressure varies accordingly.

To clarify the two values visible in the sensor screen:

Ambient Pressure: raw value measured directly by the sensor
Barometric Pressure: sea-level compensated value calculated by the software, based on the calibration elevation

Observed behavior

With the device stationary, ambient atmospheric pressure varies (normal weather variation). I would therefore expect:

barometric pressure (at sea level) to vary accordingly
elevation gain to remain stable at zero

Instead, I observe the opposite:

barometric pressure remains constant
elevation gain increases as ambient pressure changes

This behavior is consistent with the device operating in altimeter-only mode: it interprets the meteorological pressure variation as a vertical displacement, recalculates elevation upward, and the sea-level compensation remains artificially stable. This happens while stationary, which is exactly when AUTO mode should not behave this way.

Ruling out hardware failure

If this were a physical sensor issue, raw readings would be erratic and random. The firmware logic of AUTO mode would apply regardless. The fact that a systematic and consistent pattern is observed instead suggests a software problem, not a hardware one.

Hypothesis

I suspect the latest firmware update 27.09 introduced a regression in the movement detection algorithm used by AUTO mode, causing the device to behave like an altimeter even when stationary.

Has anyone else experienced this issue? Can anyone verify the behavior on a previous firmware version?

RE: Wrong elevation gain in AUTO Sensor Mode – possible firmware 27.09 bug

SAMONZEWEB — Sun, 31 May 2026 13:23:47 GMT

Same hier. My FR255 reports ridiculously high elevation gains after a run or a bike ride. FW version 27.09.

The altitude graphs seem ok, without abnormal altitudes. A bit noisy sometimes, though. Nothing that could explain the very big elevation gain at a glance.

As an example yesterday my bike ride had around 400m of elevation gain, but the watch shows around 1700m ! The graph is ok, the max altitude is almost exact. And I,ve cleaned the altimeter/barometerhole multiple times.

The elevation gain was sometimes funny, but recently it's ALWAYS way too high.

My old Hammerhead Karoo has no problem at all. Never.

I won't buy another Garmin with such nasty problems.

montre garmin forerunner 255

2054285 — Wed, 27 May 2026 12:04:47 GMT

suite a une décharge complete de batterie apres rechagre celle-ci ne s'allume plus un triangle bleu apparait

merci pour votre aide

Worst customer support ever - Forerunner 255 & 27.09

2022258 — Fri, 15 May 2026 21:24:55 GMT

[View:https://youtu.be/AVJtx2jSqR4:640:385]

I just had the worst experience with Garmin support over the last few weeks!

It started with the watch (a Forerunner 255 with software version 27.09) randomly shutting off, the battery draining within ~30 minutes at random, and the watch getting very hot in the meantime (apart from that the battery was completely fine with no issues in the past). Suddenly, the watch randomly stopped tracking during training for intervals (my last half marathon was only 18 km long according to the watch, so pacing using the Garmin was impossible). Heart rate data and elevation data were completely messed up, too. All these issues are things, which have been reported over and over again with Garmins most up-to-date software version 27.09 for this watch.

Because this is not weird enough, the watch would randomly set itself up in English, and the distances in Miles. Not even the time on the watchface was accurate anymore, jumping between completely different times.

Resetting the watch helped reduce these issues for a while, but they came back over and over. When talking to the Garmin support, the only thing they would suggest would be to reset the watch, again and again. Apart from that, the only thing they were willing to offer, was for me to buy a refurbished watch off them, or to get a discount on a different model - even though this clearly is an issue with the software they provide, and the watch itself is not broken. According to the support, this is an issue with the watch battery getting weak over time... sure. When referring to all the issues with 27.09 listed in this forum, the representative just claimed that this is anyways the same four people complaining over and over, and that there is no issue with their software whatsoever.

This definitely will have been the last Garmin device that I or anyone I know bought. Everyone always kept raving about how great Garmin support is, but at least here in Germany, they simply suck!

RE: Worst customer support ever - Forerunner 255 & 27.09

magus76 — Tue, 26 May 2026 11:56:54 GMT

After few trainings I can confirm that rolling back to 23.20 solved all my issues with 27.09. BTW. links to older sw and instructions are provided here: Guide to downgrade firmware . (remember abut the sattings backup)

RE: Garmin, can you please upload firmware 26.08?

SwimSim — Fri, 22 May 2026 20:56:52 GMT

The disappointing thing is that the list of bug fixes doesn’t mention the main issues with the altimeter, the heart‑rate monitor, or the handling of external sensors.

Garmin, can you please upload firmware 26.08?

1009563 — Tue, 17 Mar 2026 23:11:28 GMT

Garmin, please read on. Seriously your 27.09 firmware is terrible. My altimeter reading started to misbehave since upgrading to 27.09. I am now 7000 metres below sea level.

I tried re-calibration and factory reset, but one of which worked.

The only solution is for you to share 26.08 with us, so I can downgrade.

Please - you have to listen!

RE: Garmin, can you please upload firmware 26.08?

1009563 — Fri, 22 May 2026 01:19:42 GMT

hopefully 28.03 works well. if it does, i will not do a firmware update again in future - too scary.

RE: Garmin, can you please upload firmware 26.08?

1009563 — Thu, 21 May 2026 23:51:50 GMT

not available to me yet - but looking forward to it.

RE: Forerunner 255 27.09 issues

Garmin - LF — Thu, 21 May 2026 21:51:52 GMT

Our support team would like to help with this concern; we've sent you an email requesting more information. Please respond to that email so we can further assist.

Forerunner 255 27.09 issues

9148559 — Tue, 19 May 2026 20:18:50 GMT

I have had many issues just recently with my FR 255. It all started roughly two months ago - I think a software update rolled out and it drained the battery/watch got super hot in like 5 minutes. After that I got the boot loop and had to perform a hard reset. The watch worked okay for a few weeks, but just this past weekend I no longer am able to start activities, even ones that don't require GPS. When I push the start button the watch just restarts. I tried plugging the watch in and checking for updates, and I went through multiple factory resets but this time it doesn't do anything. What the heck Garmin???

RE: Garmin, can you please upload firmware 26.08?

ovekvam — Thu, 21 May 2026 07:31:02 GMT

Interesting. That means 27.09 will not be the last firmware for our watches.

RE: Worst customer support ever - Forerunner 255 & 27.09

Jacquers — Thu, 21 May 2026 06:50:21 GMT

The new beta might be worth trying: forums.garmin.com/.../public-beta-version-28-03---20

RE: Forerunner 255 27.09 issues

Jacquers — Thu, 21 May 2026 06:46:49 GMT

The new beta might be worth trying: forums.garmin.com/.../public-beta-version-28-03---20

RE: Garmin, can you please upload firmware 26.08?

Jacquers — Thu, 21 May 2026 06:42:36 GMT

There is a beta 28.03 available. Might be worth trying.

RE: Forerunner 255 - when Training Readiness will be available?

Splat — Wed, 20 May 2026 16:04:13 GMT

Garmin said the FR255 was never getting training readiness when the FR 265 ws released. it is now a 4 year old watch so... I'm certain it is still never.

Forerunner 255 - when Training Readiness will be available?

4247424 — Wed, 08 Apr 2026 08:54:46 GMT

When Training Readiness will be available in Forerunner 255?

RE: Forerunner 255 - when Training Readiness will be available?

4215794 — Tue, 19 May 2026 17:00:42 GMT

Also want this on 255, but I find HRV+load+sleep score to be pretty good indicator of my readiness to train. Then again, I mostly decide if I get to train by feel.
It's likely they will never add this feature, but only time will tell.

RE: How to log Assisted Pull-up?

8453779 — Tue, 19 May 2026 16:01:39 GMT

Unfortunately I have no idea but I second this! There are hundreds of exercises that I've never even heard of, it would be great to have assisted pull-ups where it is possible to enter a weight..

How to log Assisted Pull-up?

8917276 — Wed, 26 Nov 2025 19:14:10 GMT

Hi, I can't find any option to log Assisted Pull-up. App doesn't allow to log weight in the negative. Unsure what's best way to log it.

Battery drain 27.09

shefski — Sat, 24 Jan 2026 10:50:11 GMT

Hi, after recently updating to 27.09 on my forerunner 255, the battery life decreased drammatically (from 15 days to 1.5 days). Also, the sleep tracking no longer works and I feel like the watch has gotten slightly laggier. I have already restarted and reset my device a few times with no results.

Is this something others are experiencing as well? What's the procedure to fix this?

Thank you!