Debian 8: synchronization cannot be performed

[francesco1119]

On he top left of my screen I see a banner saying:
"synchronization cannot be performed
server couldn't respond with node tree structure"

The terminal stops with:

[Fatal Error] :1:1: Premature end of file.
4807 [PydioScheduler_Worker-1] INFO  root  - This pass took 3257 milliSeconds (Local : false)
4828 [PydioScheduler_Worker-1] INFO  root  - Checking local repo folder: /home/bobby/Pydio
4828 [PydioScheduler_Worker-1] INFO  root  - Local repo exists - OK
4970 [PydioScheduler_Worker-1] INFO  root  - PREVIOUS INDEXATION
5404 [PydioScheduler_Worker-1] INFO  root  - This pass took 592 milliSeconds (Local : true)

My Java version is:

java version "1.7.0_111"
OpenJDK Runtime Environment (IcedTea 2.6.7) (7u111-2.6.7-1~deb8u1)
OpenJDK 64-Bit Server VM (build 24.111-b01, mixed mode)

[francesco1119]

Problem persists also with Java version:

openjdk version "1.8.0_91"
OpenJDK Runtime Environment (build 1.8.0_91-8u91-b14-1~bpo8+1-b14)
OpenJDK 64-Bit Server VM (build 25.91-b14, mixed mode)