After update august 1. my Avast disappeared from my phone, and I’m not able to re-install it. I get a message saying that program can’t be installed due to a fault “504”.
Phone is a HTC One M7
Android version: 5.0.2 (Lollipop)
HTC Sense-version: 6.0
I have a Samsung Galaxy running the same program without problems, Android version: 6.0.1 (Marshmallow).
Please try to clear the Google Play Store and Google Play Services data, it might help.
I completely removed Avast from my Google Play collection.
Deleted data in “Google Play Store”
Deleted data in “Google Play Services”
Deleted data in “Download Manager”
Deleted data in “Google Services Framework”
Restarted phone
Tried to install Avast… Still “Error 504”
I have also tried to uninstall my Google Account, restart my phone and re-install my Google Account.
That didn’t help either 
Hi, so we have successfully reproduced the issue and there really is a bug. It should be fixed in about 2 or 3 weeks in version 6.12.1, thanks for your patience.
Thank you very much Tereza 
Having the same problem on my HTC Device. Also Avast Cleanup can’t be installed. Neither by GooglePlayStore nor by download on the avast.com website. Install fails after downloading getting error -504. The Link in the error message for help/support is un-clickable.
HTC One
HTC Sense Version 6.0
Software Number 7.19.401.51
HTC SDK API Level 6.55
Android 5.0.2
Avast Mobile Security 2018 and also Avast Cleanup were both installed 2 weeks ago. It appeared suddenly with an “Unable to update - Error -504” message via Google PlayStore. Deinstalling ande reinstalls not successful.
Please provide a fix/patch/workaround for HTC Users. ASAP. Thank you, developers.
Kaspersky’s similar free product is installed without problems, but is not my first choice. But it solves temporarely this “buggy” problem for me on my device.
Hi, thanks for reporting the issue, we have already started the 6.12.1 version staged roll out (at the moment released to 1% of users).
Hi, Tereza V.,
thank you for your response and the information.
Hi Tereza
I’m afraid there must be another bug!
I’m still unable to install ver. 6.12.1 & 6.12.2 
The staged roll-out is not complete yet - the 6.12 version has been released to 10% users at the moment. You can try to become a Beta tester (more on https://goo.gl/r8UPdZ) or wait a few more days.
Hi again Tereza
This problem is beginning to be annoying!
I have tried to install ver. 6.12.1, 6.12.2 and now latest 6.12.3 (updated september 4.), everytime preparing by:
Completely remove Avast from my Google Play collection.
Delete data in “Google Play Store”
Delete data in “Google Play Services”
Delete data in “Download Manager”
Delete data in “Google Services Framework”
Restart phone
I’m a happy user of Avast on my Samsung and my stationary computer, but I would appreciate a lot if you could please provide a solution that will work on my HTC phone?
Hi, sorry to hear that. I will ask my colleague to contact you - he is the best in finding solutions for such mysteries 
He will get back to you after the weekend.
Hi
I have the exact same problem.
Also, the same phone and software versions as Cíöcneli, i.e.
HTC One
HTC Sense Version 6.0
Software Number 7.19.401.51
HTC SDK API Level 6.55
Android 5.0.2
/Rickard
Hi, two days ago Google has managed to fix the -504 error (instalation/upgrade), the fix will be included in build pluginu 3.3. As soon as it is released, we will fix the issue on our side. Thanks for your patience.
Hi
My Avast has been working allright for some time, but now I´m unable to install again!
This time it says fault “910”.
Please advice…
Hi, this is a bug, known for quite a while. We are waiting for Google Play to fix it on their side, then we should be able to fix it on ours.
Just to add - same issue here on my HTC One M7.
I’ll await update - hopefully soon.
Hi,
Same problem with a new HTC One - Android 5.0.2 - HTC Sense 6.0
It’s annoying not to have an AV, and I wish I could sty with Avast…
When should it be repaired ?
Hi,
Dropped just to say that I’m too waiting for the 910 error fix for the HTC device.
Are there any guesstimations when this fix may be delivered?
Also how is it possible that competition’s product installs without trouble while Avast not? Is this really a problem with Google Play only with no possible workaround on your side?
Hi
Still waiting…!
Just tried to install version 6.16.4, dated february 8.
The problem is still there!
This is absolutely unacceptable, and I would like very much to have an update on the situation, please.