Header and footer bar flicker

since a few days ago I register a strange behaviour of my K9 app. When I open a message on tapping on the subject in the folder view it opens in the message view. In the message view the header bar with the subject and the K9 logo on the left and the footer bar with the action icons (delete, forward, reply,…) flicker for about 1 second between a lighter grey I’m used to and a darker grey. Afterwards they stay on the darker grey, I never saw until a few days ago.
I use K9 in version 5.600 on Android. I don’t remember any update (app or system) or settings modification last week, when the problem occured first.
What causes this behaviour and how can I change design to the standard grey from before without any flickering?
Thanks in advance

I haven’t heard reports about this before. Could it be a hardware defect?

I don’t think it’s a hardware issue because it’s not linked to a certain area of the device screen but to the GUI elements. The same thing happens no matter if I use the phone in landscape or portrait mode. I did a screen video and hope it can provide some useful information: https://www.youtube.com/watch?v=F4OKiF79Ut4
It seems to me that the flickering indicates the loading and/or rendering process while the app is busy(?)


I’ve been using k9 for years now and never had any issue until recently. But now I observe the same flickering behavior.

The app now randomly makes the screen flickering when scrolling certain emails.
It does not happen with all emails though.
I had restarted the app, restarted the phone entirely but this behavior still occurs. The parts that flickers are the lower menu bar and the upper bar where the email subject and k9 icons are as the original post mentions. The bar then also switches to dark gray.

I have temporarily switched to the Dark theme and it seems the issue is not present (at least not visible at the moment) so it might be related to the light theme only.

For the moment, I am reluctant to uninstall and reinstall the app since I do not want to have to reconfigure all my various email accounts and customized settings. So I do not know if the issue is persistent once the app is reinstalled.

It’s weird that the problem started without any Android/K-9 updates. If you want, you can try to join the beta test. Maybe that is already enough to fix the problem. The beta version is ready for daily use and mainly missing the “push” feature (eg. you have to set the app to look for new emails every x minutes).

I’ve had exactly the same thing, also a recent problem, i.e. past week or two.

Have the exact same issue. Only happens with the light theme, dark is ok. Android 9 samsung stock version update oct 2020 on galaxy s8

Same here. Started some weeks ago.


Same here. SGS8 / Android 9.

K-9 Mail 5.600 was released in 2018 and hasn’t been updated since then. So it’s very likely that this was caused by an OS update (or maybe a system WebView update). Please contact your device manufacturer to let them know about the problem.

Chances are the current beta version of K-9 Mail doesn’t have this issue. Please give it a try. Instructions here: How do I become a beta tester?

Same here, it started a few weeks ago. Sony Xperia XZ Premium, Android 9. No OS updates since maybe 2 years ago :joy:.
K-9 version 5.600, and it’s (strangely?) copyrighted this year:
“Copyright 2008-2021”

Same here - started yesterday. Google Pixel 3xl - Android 9. K-9 ver 5.6

Zero system updates. Disabled the Android Webview implementation and only use the one that’s built into Chrome. I tried updating Chrome - no effect. Rebooted the phone, no effect.

I have 6 email accounts on this phone, would prefer to not fool around with Beta software. Either it’s fixed and I upgrade or it doesn’t and I don’t. Use the app for work.


I found this searching for K-9 flickering behaviour, also just started a few days ago without any known updates on my end (at least no conscious ones). I was afraid this might be a virus or something but apparently more folks are experiencing this.
K-9 Version 5.600, Android 9 on Huawei Media Tab, EMUI Version 9.1.0

Hello, same here on my mobile: Motorola moto x4, Android 9, K9-mail Version 5.600
The flicker is visible in light design only - and this flickering only stops, when the message was downloaded completely .
The behaviour startet a few weeks ago.

Same for me using a Sony Xperia XZ1.


I have noticed this exact issue for the past week or more. I had just ignored it previously until seeing that others are having the problem too. Ver 5.6.

Same here 5.733, Samsung S20, UI 3.1

I’ve been having this problem, too. Running 5.600 on Android 9 on a Nokia 8. I first noticed the problem in February or March of 2021. Can’t seem to get rid of it.

When I scroll messages up and down, the top and bottom bars flicker between a lighter gray and a darker gray, usually settling on the darker gray. Then it resets to the lighter gray when I go back out to the message list.

I’ve cleared data, and even uninstalled/reinstalled the app, manually putting back in all the info for my email accounts. That seems to solve the problem briefly. After a few uses of the app, the problem returns.

So, I finally decided to revert from version 5.600 back to version 5.503. That seemed to solve the problem.

v5.503 appears to be the last version before v5.600. It appears that v5.503 is backwards compatible with settings exported from v5.600. So, I’m happy now.

Here’s source and APK for 5.503.

I was wrong. This didn’t work. After less than a day, the gray flickering started occurring with version 5.503 also.