SSLPeerUnverifiedException with Android SDk

[Graham B.]

My app uses the Dropbox Android Core SDK. One user has sent in some log data showing that our app is unable to connect to Dropbox.

(Apologies for the slightly Proguard-obfuscated stacktrace):

E/YNAB (31699): com.dropbox.client2.a.g: javax.net.ssl.SSLPeerUnverifiedException: No peer certificate
E/YNAB (31699): at com.dropbox.client2.m.a(RESTUtility.java:420)
E/YNAB (31699): at com.dropbox.client2.m.a(RESTUtility.java:339)
E/YNAB (31699): at com.dropbox.client2.a.a(DropboxAPI.java:1388)
E/YNAB (31699): at com.dropbox.client2.a.a(DropboxAPI.java:1336)

This user's phone is apparently a Blackphone, which apparently uses a hardened Android OS; see https://blackphone.ch/
This particular stacktrace comes from an older version of our app which also uses a slightly older version of the Dropbox SDK, but the user reports the same failure with the latest version of our app using v1.6.2 of the Dropbox SDK.

Is there anything I can do as an app developer to mitigate this particular error, or is there anything I can suggest to this user as a workaround?

[Greg-DB]

Thanks for the report! Do you know if this works on other phones running this operating system, or does this happen for all such phones with this OS? I suspect it is due to the certificates (or lack thereof) installed on this particular OS.

[Graham B.]

It's the only report we've had, probably from the only one of our users who happens to have this particular kind of phone.

Does Dropbox require some unusual certificates to be installed?

[Greg-DB]

Thanks! I imagine you haven't been able to reproduce this then?

Anyway, I don't believe there's anything unusual about about our certificate chain. I've taken a screenshot here:

https://www.dropbox.com/s/r2u82pm61kakjr0/Screenshot%202015-01-05%2010.47.35.png?dl=0

Maybe this device doesn't have the necessary Go Daddy certificates? Can you ask the user to check/install them if so?

[William M.46]

I'm having the same problem, on a Samsung tablet running Lollipop. On the same device, the DropBox app itself works fine.
Is there a clear work-around?

[Greg-DB]

[For anyone following along, William posted about this issue with more details in a new thread so we'll follow up there: https://www.dropboxforum.com/hc/communities/public/questions/203848175-SSLPeerUnverifiedException-fr... ]