this problem had been discussed at least 2 times
Repository with SSL - problem in to do the download - General - F-Droid Forum
Trust anchor for certification path not found - General - F-Droid Forum
using samsung galaxy tab s2 lte with android 7. there are no new updates from samsung. i get this error by adding the newpipe repo.
now i have to rely on f-droid team to deliver updates as soon as possible (that’s why i used the newpipe repo - fast update deliveries)
and Running on old Android versions | F-Droid - Free and Open Source Android App Repository
/LE: future reader, if your dumblovely device won’t allow you to add system certificates, try to add them in Android Settings > WLAN / Network -Wi-Fi > Additional Options, and then instead of WLAN select something like VPN and Apps
i posted this on my own, i am hueldoeu
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I own a Galaxy Tab S2 (Model number: SM-T710) which uses Android version 7.0 (according to the section “Software information” in “Settings” on that device).
I downloaded F-Droid.apk from https://f-droid.org/ today (2025-07-08T00:39:58+0000) and installed it (the version installed was 1.21.1). On the main window of F-Droid, I slided down to update the repositories, and the following message was shown in the notification bar:
F-Droid
Updating repositories. Connecting to https://f-droid.org/repo
(the progress bar was going from left to the right repeatedly, there was no progress)
After a few minutes, the following error was temporarily shown at the bottom of the screen:
F-Droid: java.security.cert.CertPathValidatorException: Trust anchor for certification path not found. java.security.cert.CertPathValidatorException: Trust anchor for certification path not found.
I searched related information on the internet and found this post https://community.cloudflare.com/t/net-err-cert-authority-invalid-on-some-phones/508289/ on a Cloudflare forum that is related to the error NET::ERR_CERT_AUTHORITY_INVALID. This answer https://community.cloudflare.com/t/net-err-cert-authority-invalid-on-some-phones/508289/11 mentions:
Are the affected devices running ancient versions of Android that are long out of support?
According to this website, https://endoflife.date/android, the end of Security Support of 7.0 Nougat was 01 Oct 2019.
I lack knowledge on how Android devices use certificates to interact with websites, but I assume from that comment that old Android devices might present problems when connecting to some websites on the Internet because they are using an old Android version.
I’m wondering how I could update F-Droid repositories on this device.
When I visited https://f-droid.org using the factory version of Google Chrome (version 62.0.3202.84) on that device, I get this error:
Your connection is not private
Attackers might be trying to steal your information from f-droid.org (for example, passwords, messages, or credit cards). Learn more
NET:ERR_CERT_AUTHORITY_INVALID
[ADVANCED] [Back to Safety]
When I press “ADVANCED”, the following information is shown:
This server could not prove that it is f-droid.org; its security certificate is not trusted by your device's operating system. This may be caused by a misconfiguration or an attacker intercepting your connection.
[Proceed to f-droid.org (unsafe)]
In contrast, when I updated Google Chrome using Play Store and the version shown in “Settings” for Google Chrome was 119.0.6045.193. The error NET:ERR_CERT_AUTHORITY_INVALID was not shown by Google Chrome when visiting https://f-droid.org/
Perhaps, this behavior has to with the fact that I can’t update the repositories on F-Droid.
I just found this post Trust anchor for certification path not found - 2 which is related to this issue. I didn’t find on my initial searches for the Internet, because I didn’t search for the string Trust anchor for certification path not found when I started looking for information.
Sorry for the noise.
I would suggest not deleting my post because some people might find it when searching NET:ERR_CERT_AUTHORITY_INVALID on search engines.
I have the same problem with my android-7 tablet. Android-7 does not allow to install new system-certificates 
(this was fixed in android-7.1 which is not available for my tablet).
My only workaround: Install a webbrowser that has it-s own certificate chain.
this browser can download apps via the f-droid web site that can be locally installed.
We have mirrors, pull to refresh after a 15 seconds pause, retry, until you get a better mirror.
It’s not a system certificate but a “user” certificate. But yes, there was an issue with Android 7 and certs
how is this possible?
just to add my 2 cents, there are other sites and apps to download apk-files for samsung galaxy tab s2 lte
and for my samsung galaxy tab E (i think it had android 4.4, prehistoric!!!) i installed dotOS, activated adoptable storage after inserting a 512 gb microSD and download videos and photos in whatsapp of certain groups and never have to delete anything. i had to install GApps. i have written my experiences somewhere on the internet, absolutely perfect setup and very economical.
i think i didn’t even had to migrate whatsapp to the microSD card. i have no idea what’s so bad about adoptable storage (using the microSD card as internal storage).
so stock-ROM is always an alternative.
We merge topics for tde same issues
Mostly that if something happens to break the phone, you can’t just remove the SD card and put it in a card reader on a windows system to easily recover your files. While modern linuxes can mount it if you have prepared for this possibility by extracting the encryption keys before any disaster strikes, there is a hassle factor in doing this, and of course most people will not have taken that precaution beforehand.
In other words, the same situation you have with the phone’s internal storage - it won’t be (or rather, your data residing there won’t be) removable in any useful way.
