How to fix pin required after phone restarts issue – random reboots?

Before we tell you about the “how to fix pin required after phone restarts issue”, let’s discuss some basic stuff. You probably know how Android device security works. Even if you use Face Unlock or Fingerprint Unlock, your phone will ask you to enter a PIN code, as a backup unlock option.

And every time the device restarts, you will be prompted by a message which says “pin required after phone restarts”. That’s by design, and is a security measure placed by Google.

But what if your phone is displaying the message randomly, when you use the phone? That shouldn’t be happening. It did for me, and this is how I solved it.

What happened

You can skip this section and scroll down to the “How to fix pin required after phone restarts issue” section, if you just want to know how to fix the issue. If however you want to know how I discovered the fix, read on.

A few days ago, I woke up in the middle of the night, and casually checked my phone (an ASUS Zenfone Max Pro M1) for any notifications. Oddly, it said pin required after device restarts. I didn’t reboot the phone manually, and there wasn’t any recent update. Perhaps it was a random reboot.

The next morning, I encountered the exact same message. Now I knew, something wasn’t right. Upon using the phone for a while, I noticed that the issue recurred randomly.

Sometimes it would happen after 5 minutes, sometimes after an hour or so. But it did, and it was annoying. This is when I noticed something odd, the phone didn’t actually reboot. The screen turned black, the power button didn’t respond, and about 2-3 seconds later it was on the enter your pin screen.

So, it was a soft reboot. If you aren’t familiar with the normal reboot process, lemme explain. When your phone reboots, you will see the Android logo, your device manufacturer’s logo, and it usually takes much longer, like 15-30 seconds. In my case this wasn’t happening, it was a soft reboot which is much faster.

Anyway, back to our story, this is when something really bizarre happened. We have 3 Max Pro M1 phones at home, and I discovered that a second phone was displaying the exact same symptoms. What are the chances of the issue occurring on the same day, right?

The diagnosis

Both devices were on the latest firmware, used the same network, etc. This seemed like a software issue, and normally users would either wipe the cache, or do a factory reset, or in the worst case, take the phone to the service center.

But, I decided to investigate further, hoping to discover how to fix pin required after phone restarts. I began retracing my steps for the past few days to see if something had triggered the issue. I had been tinkering with the Night mode (built-in settings) a couple of days before the issue occurred. So, I disabled that to see if it fixed the problem. It didn’t.

I then remembered that during the Android Pie Beta, the Night Light option wasn’t available and I had to enable it from the Developer options (even though it didn’t work). I disabled this too, hoping it would fix the issue, it didn’t.

The culprit

Then it hit me, the 2 phones had something else in common. Something which the 3rd phone (which was unaffected) didn’t have. I had enabled Adguard DNS on the 2 phones, when I updated the devices to Android Pie. Could this really be causing the issue?

There was only one way to be certain. I disabled the DNS on one of the phones, and the problem went away. Since it was a randomly occurring issue, I wasn’t certain even though some hours had passed without the problem re-surfacing.

Meanwhile, the other phone continued to display the pin required after phone restarts screen. So, I disabled the DNS on the 2nd phone, and guess what? It fixed the issue. This was the confirmation I needed. I don’t know why the DNS started acting up now, since it didn’t give me any problems for the past few months.

How to fix pin required after phone restarts issue

1. Open the Settings app.
2. Navigate to Network & Internet.
3. Select Advanced.
4. Tap the Private DNS option, and select off.

Of course, this fix only applies if you are using a DNS. If you aren’t, you should analyze further and consider performing a factory reset or take the device to the service center.

You don’t have to reboot the phone after this. You can try re-enabling the DNS after sometime if you want to, or switch to a different one if needed.