✏ A little Guide to... Random Reboots

This collection of troubleshooting advice for random reboots was formerly the first post of this topic (please continue there if you have questions about the guide or want to share your experiences). I now made it into its own wiki topic and gave it the unique tag rebootsguide to make it more visible (and hopefully to encourage people to keep it up to date).
For troubleshooting reboots on FP2 you may also have a look at the official support pages and select → Fairphone 2phone reboots there.

First things first

  • Update your OS (check the updater app for updates and also compare the version number there with the oslist. Generally there should be an update once a month). 18.03.1 contains the special update which fixes most reboots for phones bought in Q3/4 2017 or Q1 2018.
    • If you first experience this issue right after an update (or if it gets worse after one), chances are that it’s not actually caused by the new OS version, but that something went wrong during the update process. In that case (manually) reinstall the OS.
  • Make a dic:backup to prepare for steps that might mess with your data.

Remove well known root causes

one by one to find out which is the root cause for your reboots issue and then get rid of it permanently.

  • Take off the Cover The first charge of slim covers commonly had an issue that would cause the power button to be pressed and the phone to reboot. If the phone still reboots without the cover there is a small chance that the smaller button on the core module has an issue. Keep that in mind while checking for other known causes listed below.
  • Take out all cards (SIMs & SD)
    • If you don’t have the reboots then, put them back in one by one.
    • If one card seems responsible for the reboots get a new one. Most providers give out replacement SIMs for cards older than one or two years for free.
    • Configure your SD card as external storage. It’s often reported that SD cards used as internal storage may lead to instability.
  • Boot to safemode to see if it’s caused by a 3rd party app. (:warning: you’ll loose your widgets and some settings)
  • Disable 4g
    • if this helps again it could be the SIM card, or it could be a software issue (see bug report #86 here).
  • Disable WiFi
    • keep an eye on your phones reboot behavior for some time. If it performs more stable then read on here. Wifi (specifically 2,4GHz) in some cases cause reboots as well.

Investigate further

  • Try to find a pattern/ when do the reboots happen?
    • If it happens while charging, try different cables/chargers (see chargers list)
    • If it happens while using a specific app, clear that app’s cache (in Settings → Apps). If that doesn’t help try reinstalling that app (might cause app data to be lost) or remove the app’s data (also in Settings → Apps). If the app still causes reboots try to find an alternative or contact the app’s developer to file an issue report.
    • If it happens when the phone is exposed to small shocks or pressure the battery might not be sitting tightly, see here for a DIY fix.
    • If it happens when the phone gets hot disassemble it and clean the connectors. If it still happens it might be a hardware issue (if you’re lucky it’s a small module).
      Some very demanding apps (e.g. hd games and navigation apps) are also known to overstrain the phone’s hardware and cause reboots. Try to close all other apps and background activities and disabling all non-essential connections while using such apps.
      Extra tip: If your reboots are driven by high cpu temperature and you don’t want to claim your phone at support you can try to tweak your CPU settings (but you have to root your phone). See this post (and forwarded posts): Most sustainable way to replace FP2: Better now then wait until it dies? Opinions?
    • If it happens when making a call, after having chosen one of the two sim cards for the call, try to wait for ~5 seconds before choosing the sim card for the call.
    • If you know how to, try to debug (adb, logcat, …)
      On standard Fairphone OS you can enable the Hickup App in Settings > Maintenance to automatically send anonymized crash reports to Fairphone.
  • Try out a different operating system (OS). A list of alternatives can be found here.
  • If nothing else helps, reset
    • make a dic:backup if you haven’t yet
    • make a dic:hardreset
    • if you still have the issue after the reset, without any cards inside the phone and without any 3rd party app installed it’s quite obvious you’ll need a replacement.

Contact support

As suggested in FP’s official troubleshooting tool contact support stating the following:

Subject: “Random Reboots”
Description: “Troubleshooting instructions diagnosed the Fairphone to suffer from random reboots. I confirm that my shipping address is correct. Please help me further.”
your order number
your phone’s IMEI1

After you sent the request it’s recommended to call support with your ticket number ready as personally discussing an issue will lead to it being handled and fixed much faster than a back and forth via email (see contactsupport for more info).