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Flask-Migrate cannot downgrade to a down_revision with merged heads

I have got this weird issue I ran into when downgrading my migration versions in Flask using Flask-Migrate.
I have this merged head revision which happened from branching and an alembic merge heads.
"""empty message
Revision ID: 3ad527666180
Revises: ecd1f453d08e, 7112dcc79711
Create Date: 2021-11-11 12:17:31.973196
"""
from alembic import op
import sqlalchemy as sa
# revision identifiers, used by Alembic.
revision = '3ad527666180'
down_revision = ('7112dcc79711', 'ecd1f453d08e')
branch_labels = None
depends_on = None
def upgrade():
pass
def downgrade():
pass
When trying to downgrade to preceding revision which is 7112dcc79711, I get this error
docker exec -it users python manage.py db downgrade
/usr/local/lib/python3.7/site-packages/authlib/integrations/flask_oauth2/authorization_server.py:73: AuthlibDeprecationWarning: Define "get_jwt_config" in OpenID Connect grants
It will be compatible before version 1.0.
deprecate('Define "get_jwt_config" in OpenID Connect grants', '1.0')
/usr/local/lib/python3.7/site-packages/authlib/integrations/flask_oauth2/authorization_server.py:73: AuthlibDeprecationWarning: Define "get_jwt_config" in OpenID Connect grants
It will be compatible before version 1.0.
deprecate('Define "get_jwt_config" in OpenID Connect grants', '1.0')
INFO [alembic.runtime.migration] Context impl PostgresqlImpl.
INFO [alembic.runtime.migration] Will assume transactional DDL.
Traceback (most recent call last):
File "/usr/local/lib/python3.7/site-packages/alembic/script/base.py", line 227, in _catch_revision_errors
yield
File "/usr/local/lib/python3.7/site-packages/alembic/script/base.py", line 457, in _downgrade_revs
for script in revs
File "/usr/local/lib/python3.7/site-packages/alembic/script/base.py", line 454, in <listcomp>
migration.MigrationStep.downgrade_from_script(
File "/usr/local/lib/python3.7/site-packages/alembic/script/revision.py", line 798, in iterate_revisions
assert_relative_length=assert_relative_length,
File "/usr/local/lib/python3.7/site-packages/alembic/script/revision.py", line 1295, in _collect_downgrade_revisions
assert_relative_length=assert_relative_length,
File "/usr/local/lib/python3.7/site-packages/alembic/script/revision.py", line 1154, in _parse_downgrade_target
no_overwalk=assert_relative_length,
File "/usr/local/lib/python3.7/site-packages/alembic/script/revision.py", line 1069, in _walk
raise RevisionError("Ambiguous walk")
alembic.script.revision.RevisionError: Ambiguous walk
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "manage.py", line 7, in <module>
cli()
File "/usr/local/lib/python3.7/site-packages/click/core.py", line 764, in __call__
return self.main(*args, **kwargs)
File "/usr/local/lib/python3.7/site-packages/flask/cli.py", line 380, in main
return AppGroup.main(self, *args, **kwargs)
File "/usr/local/lib/python3.7/site-packages/click/core.py", line 717, in main
rv = self.invoke(ctx)
File "/usr/local/lib/python3.7/site-packages/click/core.py", line 1137, in invoke
return _process_result(sub_ctx.command.invoke(sub_ctx))
File "/usr/local/lib/python3.7/site-packages/click/core.py", line 1137, in invoke
return _process_result(sub_ctx.command.invoke(sub_ctx))
File "/usr/local/lib/python3.7/site-packages/click/core.py", line 956, in invoke
return ctx.invoke(self.callback, **ctx.params)
File "/usr/local/lib/python3.7/site-packages/click/core.py", line 555, in invoke
return callback(*args, **kwargs)
File "/usr/local/lib/python3.7/site-packages/click/decorators.py", line 17, in new_func
return f(get_current_context(), *args, **kwargs)
File "/usr/local/lib/python3.7/site-packages/flask/cli.py", line 257, in decorator
return __ctx.invoke(f, *args, **kwargs)
File "/usr/local/lib/python3.7/site-packages/click/core.py", line 555, in invoke
return callback(*args, **kwargs)
File "/usr/local/lib/python3.7/site-packages/flask_migrate/cli.py", line 152, in downgrade
_downgrade(directory, revision, sql, tag, x_arg)
File "/usr/local/lib/python3.7/site-packages/flask_migrate/__init__.py", line 282, in downgrade
command.downgrade(config, revision, sql=sql, tag=tag)
File "/usr/local/lib/python3.7/site-packages/alembic/command.py", line 366, in downgrade
script.run_env()
File "/usr/local/lib/python3.7/site-packages/alembic/script/base.py", line 563, in run_env
util.load_python_file(self.dir, "env.py")
File "/usr/local/lib/python3.7/site-packages/alembic/util/pyfiles.py", line 92, in load_python_file
module = load_module_py(module_id, path)
File "/usr/local/lib/python3.7/site-packages/alembic/util/pyfiles.py", line 108, in load_module_py
spec.loader.exec_module(module) # type: ignore
File "<frozen importlib._bootstrap_external>", line 728, in exec_module
File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
File "migrations/env.py", line 87, in <module>
run_migrations_online()
File "migrations/env.py", line 80, in run_migrations_online
context.run_migrations()
File "<string>", line 8, in run_migrations
File "/usr/local/lib/python3.7/site-packages/alembic/runtime/environment.py", line 851, in run_migrations
self.get_context().run_migrations(**kw)
File "/usr/local/lib/python3.7/site-packages/alembic/runtime/migration.py", line 608, in run_migrations
for step in self._migrations_fn(heads, self):
File "/usr/local/lib/python3.7/site-packages/alembic/command.py", line 355, in downgrade
return script._downgrade_revs(revision, rev)
File "/usr/local/lib/python3.7/site-packages/alembic/script/base.py", line 457, in _downgrade_revs
for script in revs
File "/usr/local/lib/python3.7/contextlib.py", line 130, in __exit__
self.gen.throw(type, value, traceback)
File "/usr/local/lib/python3.7/site-packages/alembic/script/base.py", line 261, in _catch_revision_errors
raise util.CommandError(err.args[0]) from err
alembic.util.exc.CommandError: Ambiguous walk
What is the safe way to get past this issue?
I have tried removing one of the revisions which come from a production branch, leaving the other which tallies with my development branch and it didn't produce the error.
Is there an automatic and more feasible way to just downgrade without this issue?

When I got such an error I tried to find another close revision that will work
In this case:
85c43587349b -> 69914284f0b4,
3a9ce166afbb -> 85c43587349b,
885269456833, 3a9ce166afbb -> a42162b3f858 (mergepoint)
3a9ce166afbb -> 885269456833,
f725b3be6238 -> 3a9ce166afbb (branchpoint)
6c164d07441f -> f725b3be6238
When I run alembic downgrade -1 it failed and also alembic downgrade f725b3be6238
But when I tried another version it worked
alembic downgrade 3a9ce166afbb

pserve development.ini --reload: fails in windows 10 64bit

I am following an article and creating my first project,
while i try the below command; the process gets into a loop and starts a server and kills it and again starts a server and kills and it keeps doing this continuously without breaking the loop and exiting.
pserve development.ini --reload
Below is the log
//---------------------------------------------------------
Starting monitor for PID 11912.
Traceback (most recent call last):
File "<string>", line 1, in <module>
File "D:\Others\Python\myBlog\lib\site-packages\hupper\ipc.py", line 322, in spawn_main
func(**kwargs)
File "D:\Others\Python\myBlog\lib\site-packages\hupper\worker.py", line 237, in worker_main
func(*spec_args, **spec_kwargs)
File "D:\Others\Python\myBlog\lib\site-packages\pyramid\scripts\pserve.py", line 32, in main
return command.run()
File "D:\Others\Python\myBlog\lib\site-packages\pyramid\scripts\pserve.py", line 229, in run
app = loader.get_wsgi_app(app_name, config_vars)
File "D:\Others\Python\myBlog\lib\site-packages\plaster_pastedeploy\__init__.py", line 131, in get_wsgi_app
global_conf=defaults)
File "d:\others\python\myblog\lib\site-packages\paste\deploy\loadwsgi.py", line 247, in loadapp
return loadobj(APP, uri, name=name, **kw)
File "d:\others\python\myblog\lib\site-packages\paste\deploy\loadwsgi.py", line 271, in loadobj
global_conf=global_conf)
File "d:\others\python\myblog\lib\site-packages\paste\deploy\loadwsgi.py", line 296, in loadcontext
global_conf=global_conf)
File "d:\others\python\myblog\lib\site-packages\paste\deploy\loadwsgi.py", line 320, in _loadconfig
return loader.get_context(object_type, name, global_conf)
File "d:\others\python\myblog\lib\site-packages\paste\deploy\loadwsgi.py", line 450, in get_context
global_additions=global_additions)
File "d:\others\python\myblog\lib\site-packages\paste\deploy\loadwsgi.py", line 562, in _pipeline_app_context
for name in pipeline[:-1]]
File "d:\others\python\myblog\lib\site-packages\paste\deploy\loadwsgi.py", line 562, in <listcomp>
for name in pipeline[:-1]]
File "d:\others\python\myblog\lib\site-packages\paste\deploy\loadwsgi.py", line 406, in get_context
global_conf=global_conf)
File "d:\others\python\myblog\lib\site-packages\paste\deploy\loadwsgi.py", line 296, in loadcontext
global_conf=global_conf)
File "d:\others\python\myblog\lib\site-packages\paste\deploy\loadwsgi.py", line 328, in _loadegg
return loader.get_context(object_type, name, global_conf)
File "d:\others\python\myblog\lib\site-packages\paste\deploy\loadwsgi.py", line 620, in get_context
object_type, name=name)
File "d:\others\python\myblog\lib\site-packages\paste\deploy\loadwsgi.py", line 646, in find_egg_entry_point
possible.append((entry.load(), protocol, entry.name))
File "D:\Others\Python\myBlog\lib\site-packages\pkg_resources\__init__.py", line 2405, in load
return self.resolve()
File "D:\Others\Python\myBlog\lib\site-packages\pkg_resources\__init__.py", line 2411, in resolve
module = __import__(self.module_name, fromlist=['__name__'], level=0)
File "D:\Others\Python\myBlog\lib\site-packages\weberror-0.13.1-py3.6.egg\weberror\evalexception.py", line 127
except ValueError, ve:
^
SyntaxError: invalid syntax
Killing server with PID 11912.
Starting monitor for PID 4564.
Traceback (most recent call last):

It looks like the library you're trying to use isn't built for Python 3. The except SomeException, v: syntax is only valid in Python 2. In Python 3 you must use except SomeException as v:. Try running this with Python 2 or finding a newer version of this library that supports Python 3.
Python try...except comma vs 'as' in except

Retry Unhandled error in Deferred: in scrapy

I got BotoServerError in Scrapy when uploading images to AWS S3 because it happens to be a server down. How can I handle those errors so I can set the item pipeline to sleep for a while and retry uploading again?
2016-11-17 05:59:55 [twisted] CRITICAL:
Traceback (most recent call last):
File "D:\Kerja\HIT\PYTHON~1\<project_name>\<project_name>\lib\site-packages\twisted\python\threadpool.py", line 246, in inContext
result = inContext.theWork()
File "D:\Kerja\HIT\PYTHON~1\<project_name>\<project_name>\lib\site-packages\twisted\python\threadpool.py", line 262, in <lambda>
inContext.theWork = lambda: context.call(ctx, func, *args, **kw)
File "D:\Kerja\HIT\PYTHON~1\<project_name>\<project_name>\lib\site-packages\twisted\python\context.py", line 118, in callWithContext
return self.currentContext().callWithContext(ctx, func, *args, **kw)
File "D:\Kerja\HIT\PYTHON~1\<project_name>\<project_name>\lib\site-packages\twisted\python\context.py", line 81, in callWithContext
return func(*args,**kw)
File "D:\Kerja\HIT\PYTHON~1\<project_name>\<project_name>\lib\site-packages\boto\s3\key.py", line 1426, in set_contents_from_string
encrypt_key=encrypt_key)
File "D:\Kerja\HIT\PYTHON~1\<project_name>\<project_name>\lib\site-packages\boto\s3\key.py", line 1293, in set_contents_from_file
chunked_transfer=chunked_transfer, size=size)
File "D:\Kerja\HIT\PYTHON~1\<project_name>\<project_name>\lib\site-packages\boto\s3\key.py", line 750, in send_file
chunked_transfer=chunked_transfer, size=size)
File "D:\Kerja\HIT\PYTHON~1\<project_name>\<project_name>\lib\site-packages\boto\s3\key.py", line 951, in _send_file_internal
query_args=query_args
File "D:\Kerja\HIT\PYTHON~1\<project_name>\<project_name>\lib\site-packages\boto\s3\connection.py", line 668, in make_request
retry_handler=retry_handler
File "D:\Kerja\HIT\PYTHON~1\<project_name>\<project_name>\lib\site-packages\boto\connection.py", line 1071, in make_request
retry_handler=retry_handler)
File "D:\Kerja\HIT\PYTHON~1\<project_name>\<project_name>\lib\site-packages\boto\connection.py", line 1028, in _mexe
raise BotoServerError(response.status, response.reason, body)
BotoServerError: BotoServerError: 503 Service Unavailable

Thanks to #paul! Based on his answer, I solve it by uninstalling package boto and install package boto3 instead.

R CMD BATCH script.R ,execution via fabric run() never exits

I have written a fabric script with boto to install a R application on AWS instance. Fedora 23
All the commands using run & sudo function go as expected,
except this one:
#parallel
def install_DvD():
# with settings(hide('warnings', 'running', 'stdout', 'stderr'), warn_only=True):
cmd0 = 'R CMD BATCH %s/DvDdependencies.R' % (DvDpackage_location)
run(cmd0)
As you would noticed, I tried using 'warn_only=true', and that did not help. The installation completes successfully with out errors, I check that manually by logging into the instance and eyeballing DvDdependencies.Rout file.
I think for reasons unkonwn to me the R CMD BATCH command does not return the execution back to fabric.
The traceback output from Ctrl^c the fabric process on my local system is:
[ec2-54-172-154-181.compute-1.amazonaws.com] run: R CMD BATCH ~/DvDdependencies.R
[ec2-54-165-109-62.compute-1.amazonaws.com] run: R CMD BATCH ~/DvDdependencies.R
^C
Stopped.
!!! Parallel execution exception under host u'ec2-54-165-109-62.compute-1.amazonaws.com':
!!! Parallel execution exception under host u'ec2-54-172-154-181.compute-1.amazonaws.com':
Process ec2-54-172-154-181.compute-1.amazonaws.com:
Traceback (most recent call last):
File "/usr/lib64/python2.7/multiprocessing/process.py", line 258, in _bootstrap
self.run()
File "/usr/lib64/python2.7/multiprocessing/process.py", line 114, in run
Process ec2-54-165-109-62.compute-1.amazonaws.com:
self._target(*self._args, **self._kwargs)
File "/home/eyebell/local_bin/healX/DvD-installation/py2fabvirt/lib/python2.7/site-packages/fabric/tasks.py", line 242, in inner
Traceback (most recent call last):
File "/usr/lib64/python2.7/multiprocessing/process.py", line 258, in _bootstrap
submit(task.run(*args, **kwargs))
File "/home/eyebell/local_bin/healX/DvD-installation/py2fabvirt/lib/python2.7/site-packages/fabric/tasks.py", line 174, in run
return self.wrapped(*args, **kwargs)
File "/home/eyebell/local_bin/healX/DvD-installation/py2fabvirt/lib/python2.7/site-packages/fabric/decorators.py", line 181, in inner
self.run()
File "/usr/lib64/python2.7/multiprocessing/process.py", line 114, in run
self._target(*self._args, **self._kwargs)
File "/home/eyebell/local_bin/healX/DvD-installation/py2fabvirt/lib/python2.7/site-packages/fabric/tasks.py", line 242, in inner
return func(*args, **kwargs)
File "/home/eyebell/local_bin/healX/DvD-installation/fabfile.py", line 70, in install_DvD
run(cmd0)
File "/home/eyebell/local_bin/healX/DvD-installation/py2fabvirt/lib/python2.7/site-packages/fabric/network.py", line 649, in host_prompting_wrapper
submit(task.run(*args, **kwargs))
File "/home/eyebell/local_bin/healX/DvD-installation/py2fabvirt/lib/python2.7/site-packages/fabric/tasks.py", line 174, in run
return self.wrapped(*args, **kwargs)
File "/home/eyebell/local_bin/healX/DvD-installation/py2fabvirt/lib/python2.7/site-packages/fabric/decorators.py", line 181, in inner
return func(*args, **kwargs)
return func(*args, **kwargs)
File "/home/eyebell/local_bin/healX/DvD-installation/py2fabvirt/lib/python2.7/site-packages/fabric/operations.py", line 1056, in run
File "/home/eyebell/local_bin/healX/DvD-installation/fabfile.py", line 70, in install_DvD
run(cmd0)
File "/home/eyebell/local_bin/healX/DvD-installation/py2fabvirt/lib/python2.7/site-packages/fabric/network.py", line 649, in host_prompting_wrapper
return func(*args, **kwargs)
File "/home/eyebell/local_bin/healX/DvD-installation/py2fabvirt/lib/python2.7/site-packages/fabric/operations.py", line 1056, in run
shell_escape=shell_escape)
File "/home/eyebell/local_bin/healX/DvD-installation/py2fabvirt/lib/python2.7/site-packages/fabric/operations.py", line 925, in _run_command
stderr=stderr, timeout=timeout)
File "/home/eyebell/local_bin/healX/DvD-installation/py2fabvirt/lib/python2.7/site-packages/fabric/operations.py", line 811, in _execute
time.sleep(ssh.io_sleep)
KeyboardInterrupt
shell_escape=shell_escape)
File "/home/eyebell/local_bin/healX/DvD-installation/py2fabvirt/lib/python2.7/site-packages/fabric/operations.py", line 925, in _run_command
stderr=stderr, timeout=timeout)
File "/home/eyebell/local_bin/healX/DvD-installation/py2fabvirt/lib/python2.7/site-packages/fabric/operations.py", line 811, in _execute
time.sleep(ssh.io_sleep)
KeyboardInterrupt
The complete script is here in my github repo,
the location of DvDdependencies.R (the script that I want to install)
Any comments, help or pointers in right direction are appreciated.

I am closing this, as the issue is with this script only.
Also the installation method for DvD tool has been updated,
hence this is not of interest anymore.

Error while running portia on docker in ubuntu

I am getting following error while running portia on docker in ubuntu 14.04. I have gone through following answers, but they are not working.
Autobahn websocket issue while running with twistd using tac file
docker command: sudo docker run --rm -p 9001:9001 --name portia portia
Docker version 1.9.1, build a34a1d5
Twisted: 15.5.0
python - 2.7
building portia image downloaded from https://github.com/scrapinghub/portia
2015-12-12 15:34:03.676329 [HTTPChannel,56,127.0.0.1] Unhandled Error
Traceback (most recent call last):
File "/usr/local/lib/python2.7/dist-packages/twisted/protocols/basic.py", line 571, in dataReceived
why = self.lineReceived(line)
File "/usr/local/lib/python2.7/dist-packages/twisted/web/http.py", line 1676, in lineReceived
self.allContentReceived()
File "/usr/local/lib/python2.7/dist-packages/twisted/web/http.py", line 1755, in allContentReceived
req.requestReceived(command, path, version)
File "/usr/local/lib/python2.7/dist-packages/twisted/web/http.py", line 823, in requestReceived
self.process()
--- <exception caught here> ---
File "/usr/local/lib/python2.7/dist-packages/twisted/web/server.py", line 189, in process
self.render(resrc)
File "/usr/local/lib/python2.7/dist-packages/twisted/web/server.py", line 238, in render
body = resrc.render(self)
File "/app/slyd/slyd/splash/ferry.py", line 79, in render
return WebSocketResource.render(self, request)
File "/usr/local/lib/python2.7/dist-packages/autobahn/twisted/resource.py", line 162, in render
protocol.makeConnection(transport)
File "/usr/local/lib/python2.7/dist-packages/twisted/internet/protocol.py", line 487, in makeConnection
self.connectionMade()
File "/usr/local/lib/python2.7/dist-packages/autobahn/twisted/websocket.py", line 88, in connectionMade
self._connectionMade()
File "/usr/local/lib/python2.7/dist-packages/autobahn/websocket/protocol.py", line 2720, in _connectionMade
WebSocketProtocol._connectionMade(self)
File "/usr/local/lib/python2.7/dist-packages/autobahn/websocket/protocol.py", line 1187, in _connectionMade
self.openHandshakeTimeoutCall = txaio.call_later(self.openHandshakeTimeout, self.onOpenHandshakeTimeout)
File "/usr/local/lib/python2.7/dist-packages/txaio/_unframework.py", line 43, in _throw_usage_error
"To use txaio, you must first select a framework "
exceptions.RuntimeError: To use txaio, you must first select a framework with .use_twisted() or .use_txaio()
2015-12-12 15:34:03.684892 [HTTPChannel,56,127.0.0.1] Unhandled Error
Traceback (most recent call last):
File "/usr/local/lib/python2.7/dist-packages/twisted/python/log.py", line 101, in callWithLogger
return callWithContext({"system": lp}, func, *args, **kw)
File "/usr/local/lib/python2.7/dist-packages/twisted/python/log.py", line 84, in callWithContext
return context.call({ILogContext: newCtx}, func, *args, **kw)
File "/usr/local/lib/python2.7/dist-packages/twisted/python/context.py", line 118, in callWithContext
return self.currentContext().callWithContext(ctx, func, *args, **kw)
File "/usr/local/lib/python2.7/dist-packages/twisted/python/context.py", line 81, in callWithContext
return func(*args,**kw)
--- <exception caught here> ---
File "/usr/local/lib/python2.7/dist-packages/qtreactor/qt4base.py", line 100, in _read
data = w.doRead()
File "/usr/local/lib/python2.7/dist-packages/twisted/internet/tcp.py", line 209, in doRead
return self._dataReceived(data)
File "/usr/local/lib/python2.7/dist-packages/twisted/internet/tcp.py", line 215, in _dataReceived
rval = self.protocol.dataReceived(data)
File "/usr/local/lib/python2.7/dist-packages/twisted/protocols/basic.py", line 571, in dataReceived
why = self.lineReceived(line)
File "/usr/local/lib/python2.7/dist-packages/twisted/web/http.py", line 1676, in lineReceived
self.allContentReceived()
File "/usr/local/lib/python2.7/dist-packages/twisted/web/http.py", line 1755, in allContentReceived
req.requestReceived(command, path, version)
File "/usr/local/lib/python2.7/dist-packages/twisted/web/http.py", line 823, in requestReceived
self.process()
File "/usr/local/lib/python2.7/dist-packages/twisted/web/server.py", line 191, in process
self.processingFailed(failure.Failure())
File "/app/slyd/slyd/server.py", line 30, in processingFailed
return WebRequest.processingFailed(self, reason)
File "/usr/local/lib/python2.7/dist-packages/twisted/web/server.py", line 329, in processingFailed
self.write(body)
File "/usr/local/lib/python2.7/dist-packages/twisted/web/server.py", line 217, in write
http.Request.write(self, data)
File "/usr/local/lib/python2.7/dist-packages/twisted/web/http.py", line 1006, in write
self.transport.writeSequence(l)
exceptions.AttributeError: 'NoneType' object has no attribute 'writeSequence'
2015-12-12 15:34:03.685464 [HTTPChannel,56,127.0.0.1] Unhandled Error
Traceback (most recent call last):
File "bin/slyd", line 41, in <module>
splash.server.main()
File "/usr/local/lib/python2.7/dist-packages/splash/server.py", line 386, in main
reactor.run()
File "/usr/local/lib/python2.7/dist-packages/qtreactor/qt4base.py", line 282, in run
self._blockApp.exec_()
File "/usr/local/lib/python2.7/dist-packages/qtreactor/qt4base.py", line 110, in read
log.callWithLogger(w, _read)
--- <exception caught here> ---
File "/usr/local/lib/python2.7/dist-packages/twisted/python/log.py", line 101, in callWithLogger
return callWithContext({"system": lp}, func, *args, **kw)
File "/usr/local/lib/python2.7/dist-packages/twisted/python/log.py", line 84, in callWithContext
return context.call({ILogContext: newCtx}, func, *args, **kw)
File "/usr/local/lib/python2.7/dist-packages/twisted/python/context.py", line 118, in callWithContext
return self.currentContext().callWithContext(ctx, func, *args, **kw)
File "/usr/local/lib/python2.7/dist-packages/twisted/python/context.py", line 81, in callWithContext
return func(*args,**kw)
File "/usr/local/lib/python2.7/dist-packages/qtreactor/qt4base.py", line 107, in _read
self.qt_reactor._disconnectSelectable(w, sys.exc_info()[1], False)
File "/usr/local/lib/python2.7/dist-packages/twisted/internet/posixbase.py", line 260, in _disconnectSelectable
selectable.connectionLost(failure.Failure(why))
File "/usr/local/lib/python2.7/dist-packages/twisted/internet/tcp.py", line 293, in connectionLost
protocol.connectionLost(reason)
File "/usr/local/lib/python2.7/dist-packages/autobahn/twisted/websocket.py", line 98, in connectionLost
self._connectionLost(reason)
File "/usr/local/lib/python2.7/dist-packages/autobahn/websocket/protocol.py", line 2732, in _connectionLost
WebSocketProtocol._connectionLost(self, reason)
File "/usr/local/lib/python2.7/dist-packages/autobahn/websocket/protocol.py", line 1209, in _connectionLost
if self.autoPingPendingCall:
exceptions.AttributeError: 'FerryServerProtocol' object has no attribute 'autoPingPendingCall'
`