When Instant Upload attempt to upload a new picture, it will fail after 35-40% progress with "Unknown error". No corresponding log message is recorded on the server.
Steps to reproduce
1. Take a new picture with the Camera application.
Instant Upload should send the picture to the OwnCloud server without an error.
The upload aborts between 35 and 40% with "Unknown error". Retry is not successful.
Mobile client configuration
Client OS: Android 6.0.1 (Nexus 5, stock)
Client version: 2.2.0
Operating system: CentOS 6.8
Web server: nginx 1.10.1
Database: MySQL 5.5.38
PHP version: 5.6
ownCloud version: 9.1.2
Updated from an older ownCloud or fresh install: Upgrade, unsure of original version
ownCloud log (data/owncloud.log):
The desktop client works as expected for syncing. Web also works for both desktop and mobile. I can download files from the server without any incident. The camera directory has been set appropriately to accommodate changes in the latest client. I previously ran my server with IPv4 and IPv6 addresses and dropped IPv6 support to work around issue #616. I've also recently changed my server certificate from StartSSL to LetsEncrypt and verified the SSL server both in browser and using ssllabs.com.