xpra 0.0.7.29 (and above) is not backwards compatible with 0.0.7.27 (and older)

[أحمد المحمودي]

When I connect using xpra 0.0.7.29 (or later) to a machine that has xpra 0.0.7.27 (or older), I get the following error:

Attached (press Control-C to detach)
connection lost: empty marker in read queue
Connection lost

Also I noticed once that the window I am trying to attach appears momentarily then disappears and the error message appeared.

[Antoine Martin]

Good catch!
r270 fixes this - please re-open if necessary

[migration script]

this ticket has been moved to: ​https://github.com/Xpra-org/xpra/issues/38