How to Fix Random Reboots and Frequent Crashes on the Garmin Fenix 8

Causes

• Firmware bugs in early production units — the Fenix 8 launched with software versions 11.x and 12.x that contained known memory leak and kernel panic triggers, especially when switching between map pages, weather overlays, or glance widgets during an activity
• Corrupted or incompatible Connect IQ apps and watch faces — third-party apps that haven't been updated for the Fenix 8's new AMOLED rendering pipeline or gesture-based UI can allocate excessive resources and cause the system watchdog to trigger a hard reset
• Faulty GPE (Garmin Picture Engine) file — the GPE file stores activity course previews and map tiles, and a corrupted GPE file causes the watch to crash immediately when trying to start an activity or navigate along a saved route, particularly after syncing large courses from Garmin Connect
• Aggressive PCIe ASPM power management on the Fenix 8's internal storage controller — certain firmware revisions set an overly aggressive L1 substate that causes the flash storage to become unresponsive under active read/write during activity recording, triggering a spontaneous reboot
• Hydration tracking notification glitch — enabling both the hydration tracker app and its push notification simultaneously creates a recurring alarm-handler conflict in the system service layer, causing crashes at regular intervals throughout the day, as documented in multiple Garmin Forum threads
• Overloaded data screens with too many data fields per page — configuring 6–8 custom data fields on a single screen forces the watch to redraw at a rate that exceeds the display controller's buffer capacity, especially during GPS-intensive activities like hiking or trail running

How to Fix

1. Press and hold the upper left button (Light) for 15–30 seconds until the Fenix 8 powers off, then release and press it again to restart. This soft reboot clears temporary memory leaks without erasing any data. Perform this step first before trying more destructive fixes.
2. Connect the Fenix 8 to your computer via USB and open Garmin Express. Check for available firmware updates and install the latest version. As of mid-2026, software version 22.35 or newer has addressed the majority of the random reboot bugs. If Garmin Express shows no update, manually check by going to Settings → System → Software Update on the watch.
3. Remove all third-party Connect IQ apps and watch faces as a test: open the Connect IQ app on your phone, tap each installed app, and select Remove. Also go to Settings → Watch Face on the Fenix 8 and switch to a stock Garmin watch face (e.g., "Hi-Contrast" or "Digital"). Use the watch for 24 hours — if the reboots stop, reinstall apps one at a time to identify the culprit.
4. If crashes happen specifically when starting an activity or loading a course, the GPE file is likely corrupted. Connect the Fenix 8 to a computer via USB, navigate to the GARMIN/GPE folder on the watch's internal storage, and delete all files inside it (they are cached course previews that will be recreated automatically). Safely eject the watch and restart it.
5. Disable hydration tracker notifications if they are active: on the Fenix 8, go to Settings → Apps → Hydration Tracking and turn off Notifications. Leave the app itself enabled. This specific combination has been proven to trigger the recurring crash bug on firmware versions between 15.33 and 21.25.
6. Simplify your activity data screens: on the watch, open any activity profile (e.g., Run, Hike, Bike), select Data Screens, and edit each screen to show a maximum of 4 data fields per screen. Use multiple screens instead of cramming everything onto one. This reduces the display controller's rendering load and prevents the watchdog timeout crash during GPS recording.
7. If the watch continues to crash after all the above steps, perform a full factory reset: go to Settings → System →Reset → Delete Data and Reset Settings. This wipes all user data, installed apps, and settings — the equivalent of a fresh-out-of-box state. After the reset, do not restore a backup. Instead, set up the watch manually and only install critical Connect IQ apps. Charge the watch to 100% and let it stabilize for several hours.
8. If the factory reset does not resolve random reboots for a week of normal use, the hardware may be defective — specifically the internal storage controller or the mainboard power management IC. Contact Garmin Support to initiate a warranty replacement. The Fenix 8 carries a 2-year limited warranty in most regions, and Garmin has been issuing replacements for units with persistent crash behavior that software cannot fix.