The problem comes from the newer bencoders, which do not send dictionary keys in a specific order (pointless since python will immediately stick them in a dict which loses the order), solutions:
The error shows up in the server log as:
Traceback (most recent call last): File "/usr/lib64/python2.7/site-packages/xpra/protocol.py", line 575, in do_read_parse_thread_loop File "/usr/lib64/python2.7/site-packages/xpra/bencode.py", line 72, in bdecode File "/usr/lib64/python2.7/site-packages/xpra/bencode.py", line 45, in decode_list File "/usr/lib64/python2.7/site-packages/xpra/bencode.py", line 55, in decode_dict ValueError connection lost: gibberish received: 'l5:hellod16:...
this fixes the old servers
r5236 restores compatibility with old servers, backport for v0.11.x branch in r5239
Note: if you've come here because you are seeing this error, this means you are using an old, buggy and unsupported server...
this ticket has been moved to: https://github.com/Xpra-org/xpra/issues/499