I am using syncevolution 1.5.
syncevo-http-server line 362 looks like this on my Fedora 22 installation:
page = twisted.web.error.NoResource(message="The session %s was not found" % sessionid)
But since twisted release 9.0 this is deprecated and since 2 years this feature is removed. Because of this, the syncevo-http-server has to be fixed. Line 362 changes to
page = twisted.web.resource.NoResource(message="The session %s was not found" % sessionid)
and line 27 changes from
Patch included in the upcoming 1.5.1, thanks a lot.