My wife's Garmin 255 watch stopped working today - it just shows a blinking triangle. Nothing we tried so far got around that. Apparently, this is caused by a bug in a Garmin update that gets automatically installed if you connect the watch using Garmin software on your phone or computer, and affects many different Gartmin models (see www.androidauthority.com/garmin-smartwatches-bootloop-issue-3520875/).

If this has not happened to you yet, a workaround is to use file transfer software like OpenMTP instead of the Garmin software, and transfer files manually. I'm doing this with my Mac; should work for Windows, too, but I am not sure if or how this works with phones. You may have to disable something in the Garmin settings so that connecting the watch does not automatically start the Garmin software.

If anyone else encountered this issue and found a fix, please share!

Thanks Peter,
I'm going to uninstall the garmin apps on my phone just on case.

www.dcrainmaker.com/2025/01/garmin-watches-are-crashing-when-trying-to-start-gps.html

support.garmin.com/en-US/?faq=IWfNuaG0jn6d6oQ4HCVz29

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CarlosSainz said..
www.dcrainmaker.com/2025/01/garmin-watches-are-crashing-when-trying-to-start-gps.html

support.garmin.com/en-US/?faq=IWfNuaG0jn6d6oQ4HCVz29

These links have really great info on fixing the issue if you are experiencing it. Good news is, if you haven't had this already, you probably won't get the problem now as the offending file has been removed from the Garmin updates. Of course, doesn't mean it won't happen again in the future.One way to avoid this kind of problem is to disable automatic updates to your watch. That comes with its own risks of course.

Thanks Carlos

My understanding is that the issue was caused by a corrupted satellite pre-cache file. This file is important for the quick and accurate start of the watch GPS system at the beginning of a session.
I don't think disabling auto updates is a good idea or even if this would stop the issue from occurring.

I don't know if disabling auto-updates would prevent such issues. That said, I am very skeptical about auto-updates. I have run into problems with software that worked perfectly fine, until an auto-update installed a new version that broke things, too many times. This incident, and the things Mike observed with Coros firmware, illustrate that bad things can happen with auto-updates on GPS watches, too.

The good news for the Garmin watches is that there is a way to completely eliminate auto-updates, at least if you are using a computer: just use file transfer software like OpenMTP instead of the Garmin software. A little added advantage is that you get files that are properly named with a date (like 2025-01-25-16-46-46.fit), instead of a ZIP archive with a file that's just a number (like 18105751182_ACTIVITY.fit).

In Windows no software is required. The watch contents can be browsed in the same way as any USB Memory stick.

When an update is available, I get a message asking me if I want to install it. It does not happen automatically.

The problematic file isn't an update as such, just predictions of the satellite orbits to facilitate faster signal acquisition. The latest orbital predictions are periodically pushed from your phone to your watch, when the two devices sync. As boardsurfr and tbwonder suggested, I doubt that disabling auto-updates will protect you from this particular type of issue.

Yes I was one of those who had the issue, the flashing triangle, issue started for me Wednesday afternoon while powering it up from full shutdown. Thursday I did factory reset and started setup from scratch, seems ok now.

This is how I did reset

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tonyk said..
Yes I was one of those who had the issue, the flashing triangle, issue started for me Wednesday afternoon while powering it up from full shutdown. Thursday I did factory reset and started setup from scratch, seems ok now.

This is how I did reset

There are reports that the factory reset alone is not enough to fix the problem. It will stop the boot loop (flashing triangle), but the problem reappears when you start an activity. You also need to update the watch, which apparently happens automatically when you connect it to Garmin software.

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boardsurfr said..
There are reports that the factory reset alone is not enough to fix the problem. It will stop the boot loop (flashing triangle), but the problem reappears when you start an activity. You also need to update the watch, which apparently happens automatically when you connect it to Garmin software.

As noted in this thread - corrupted datafile used to initialise the GPS module, which makes the gps-reception be _faster_.

A factory-reset usually does fix the watch because the device to reverts back to its initial firmware. It is then important to do a complete system-update, which does include the fixed data-file -> this must be done immediately via Garmin-IQ. If you simply connect to the Garmin-connect app, it will send the corrupted datafile to the watch, thus causing the issue again.

For those interested.... there are a few faults here:

1/ it should be possible to create a bad datafile. The Garmin developers [ on the server side of this situation ] didn't create a test-harness which ensures the datafile is always valid.

2/ the Garmin phone apps didn't re-verify the validity of the datafile. [ ref "Crowdstrike airline outage" for a similar example ]

3/ the watch itself should have a mode where the corrupted datafile doesn't cause a crash. The watch should revert to not using a datafile at all.

There are some reports of even-on-factory-reset the watch doesn't boot, though Garmin isn't saying this exactly. This situation is likely due the initial-firmware always using the corrupted datafile [ thus possibly another coding fault ]. This may occur because the _first boot_ of the watch (say a new purchase) will always use the first-downloaded-datafile... thus no recovery is possible.... which wouldn't be an issue if item-3 had been implemented.

A interesting note... some customers complaining on some Garmin forums that they are never purchasing Garmin watches again, instead moving to Coros.

Which is ironic because some Coros are also affected, and the other Seabreeze thread is discussing its own Coros issues.

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mathew said..
There are some reports of even-on-factory-reset the watch doesn't boot

It is very easy to misread the instructions for the factory reset, and let go off the buttons in the wrong order. There may even be some instructions our there that have it wrong (there are definitely instructions with small differences). The first few times I tried to do a factory reset, it did not seem to work, but I think it probably was due to pressing or releasing buttons in the wrong order.

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boardsurfr said..

tonyk said..
Yes I was one of those who had the issue, the flashing triangle, issue started for me Wednesday afternoon while powering it up from full shutdown. Thursday I did factory reset and started setup from scratch, seems ok now.

This is how I did reset

There are reports that the factory reset alone is not enough to fix the problem. It will stop the boot loop (flashing triangle), but the problem reappears when you start an activity. You also need to update the watch, which apparently happens automatically when you connect it to Garmin software.

Thanks for the heads up. I'll keep an eye on it
Cheers TK

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mathew said..

boardsurfr said..
There are reports that the factory reset alone is not enough to fix the problem. It will stop the boot loop (flashing triangle), but the problem reappears when you start an activity. You also need to update the watch, which apparently happens automatically when you connect it to Garmin software.

As noted in this thread - corrupted datafile used to initialise the GPS module, which makes the gps-reception be _faster_.

A factory-reset usually does fix the watch because the device to reverts back to its initial firmware. It is then important to do a complete system-update, which does include the fixed data-file -> this must be done immediately via Garmin-IQ. If you simply connect to the Garmin-connect app, it will send the corrupted datafile to the watch, thus causing the issue again.

For those interested.... there are a few faults here:

1/ it should be possible to create a bad datafile. The Garmin developers [ on the server side of this situation ] didn't create a test-harness which ensures the datafile is always valid.

2/ the Garmin phone apps didn't re-verify the validity of the datafile. [ ref "Crowdstrike airline outage" for a similar example ]

3/ the watch itself should have a mode where the corrupted datafile doesn't cause a crash. The watch should revert to not using a datafile at all.

There are some reports of even-on-factory-reset the watch doesn't boot, though Garmin isn't saying this exactly. This situation is likely due the initial-firmware always using the corrupted datafile [ thus possibly another coding fault ]. This may occur because the _first boot_ of the watch (say a new purchase) will always use the first-downloaded-datafile... thus no recovery is possible.... which wouldn't be an issue if item-3 had been implemented.

Select to expand quote

mathew said..

boardsurfr said..
There are reports that the factory reset alone is not enough to fix the problem. It will stop the boot loop (flashing triangle), but the problem reappears when you start an activity. You also need to update the watch, which apparently happens automatically when you connect it to Garmin software.

As noted in this thread - corrupted datafile used to initialise the GPS module, which makes the gps-reception be _faster_.

A factory-reset usually does fix the watch because the device to reverts back to its initial firmware. It is then important to do a complete system-update, which does include the fixed data-file -> this must be done immediately via Garmin-IQ. If you simply connect to the Garmin-connect app, it will send the corrupted datafile to the watch, thus causing the issue again.

For those interested.... there are a few faults here:

1/ it should be possible to create a bad datafile. The Garmin developers [ on the server side of this situation ] didn't create a test-harness which ensures the datafile is always valid.

2/ the Garmin phone apps didn't re-verify the validity of the datafile. [ ref "Crowdstrike airline outage" for a similar example ]

3/ the watch itself should have a mode where the corrupted datafile doesn't cause a crash. The watch should revert to not using a datafile at all.

There are some reports of even-on-factory-reset the watch doesn't boot, though Garmin isn't saying this exactly. This situation is likely due the initial-firmware always using the corrupted datafile [ thus possibly another coding fault ]. This may occur because the _first boot_ of the watch (say a new purchase) will always use the first-downloaded-datafile... thus no recovery is possible.... which wouldn't be an issue if item-3 had been implemented.

Thanks Matthew